diff --git a/package-lock.json b/package-lock.json
index 43f9768d4ee..9863ec9d224 100644
--- a/package-lock.json
+++ b/package-lock.json
@@ -12725,6 +12725,10 @@
 			"resolved": "packages/php-wasm/node",
 			"link": true
 		},
+		"node_modules/@php-wasm/node-5-6": {
+			"resolved": "packages/php-wasm/node-builds/5-6",
+			"link": true
+		},
 		"node_modules/@php-wasm/node-7-4": {
 			"resolved": "packages/php-wasm/node-builds/7-4",
 			"link": true
@@ -12781,6 +12785,10 @@
 			"resolved": "packages/php-wasm/web",
 			"link": true
 		},
+		"node_modules/@php-wasm/web-5-6": {
+			"resolved": "packages/php-wasm/web-builds/5-6",
+			"link": true
+		},
 		"node_modules/@php-wasm/web-7-4": {
 			"resolved": "packages/php-wasm/web-builds/7-4",
 			"link": true
@@ -52570,6 +52578,15 @@
 				"npm": ">=10.2.3"
 			}
 		},
+		"packages/php-wasm/node-builds/5-6": {
+			"name": "@php-wasm/node-5-6",
+			"version": "3.0.53",
+			"license": "GPL-2.0-or-later",
+			"engines": {
+				"node": ">=20.10.0",
+				"npm": ">=10.2.3"
+			}
+		},
 		"packages/php-wasm/node-builds/7-4": {
 			"name": "@php-wasm/node-7-4",
 			"version": "3.0.53",
@@ -52687,6 +52704,15 @@
 				"npm": ">=10.2.3"
 			}
 		},
+		"packages/php-wasm/web-builds/5-6": {
+			"name": "@php-wasm/web-5-6",
+			"version": "3.0.53",
+			"license": "GPL-2.0-or-later",
+			"engines": {
+				"node": ">=20.10.0",
+				"npm": ">=10.2.3"
+			}
+		},
 		"packages/php-wasm/web-builds/7-4": {
 			"name": "@php-wasm/web-7-4",
 			"version": "3.0.53",
diff --git a/packages/php-wasm/compile/php-post-message-to-js/post_message_to_js.c b/packages/php-wasm/compile/php-post-message-to-js/post_message_to_js.c
index 539d60cc27b..5e14febc112 100644
--- a/packages/php-wasm/compile/php-post-message-to-js/post_message_to_js.c
+++ b/packages/php-wasm/compile/php-post-message-to-js/post_message_to_js.c
@@ -14,16 +14,22 @@ PHP_FUNCTION(post_message_to_js)
     char *data;
     int data_len;
 
-    if (zend_parse_parameters(ZEND_NUM_ARGS(), "s", &data, &data_len) == FAILURE) {
+    if (zend_parse_parameters(ZEND_NUM_ARGS() TSRMLS_CC, "s", &data, &data_len) == FAILURE) {
         return;
     }
 
     char *response;
     size_t response_len = js_module_onMessage(data, &response);
-    if (response_len != -1) {
+    if (response_len != (size_t)-1) {
+#if PHP_MAJOR_VERSION >= 7
         zend_string *return_string = zend_string_init(response, response_len, 0);
         free(response);
         RETURN_NEW_STR(return_string);
+#else
+        RETVAL_STRINGL(response, response_len, 1);
+        free(response);
+        return;
+#endif
     } else {
         RETURN_NULL();
     }
diff --git a/packages/php-wasm/compile/php-wasm-dns-polyfill/dns_polyfill.c b/packages/php-wasm/compile/php-wasm-dns-polyfill/dns_polyfill.c
index 2c96cd96bc9..5bf1c65706b 100644
--- a/packages/php-wasm/compile/php-wasm-dns-polyfill/dns_polyfill.c
+++ b/packages/php-wasm/compile/php-wasm-dns-polyfill/dns_polyfill.c
@@ -119,21 +119,27 @@ PHP_FUNCTION(dns_check_record)
 	HEADER *hp;
 	querybuf answer = {0};
 	char *hostname;
+#if PHP_MAJOR_VERSION >= 7
 	size_t hostname_len;
 	size_t rectype_len = 0;
 	zend_string *rectype = NULL;
+#else
+	int hostname_len;
+	int rectype_len = 0;
+	char *rectype = NULL;
+#endif
 	int type = DNS_T_MX, i;
 
-	if (zend_parse_parameters(ZEND_NUM_ARGS(), "s|s", &hostname, &hostname_len, &rectype, &rectype_len) == FAILURE) {
+	if (zend_parse_parameters(ZEND_NUM_ARGS() TSRMLS_CC, "s|s", &hostname, &hostname_len, &rectype, &rectype_len) == FAILURE) {
 		return;
 	}
 
 	if (hostname_len == 0) {
-		php_error_docref(NULL, E_WARNING, "Host cannot be empty");
+		php_error_docref(NULL TSRMLS_CC, E_WARNING, "Host cannot be empty");
 		RETURN_FALSE;
 	}
 
-	php_error_docref(NULL, E_WARNING, "dns_check_record() always returns false in PHP.wasm.");
+	php_error_docref(NULL TSRMLS_CC, E_WARNING, "dns_check_record() always returns false in PHP.wasm.");
 
     RETURN_FALSE;
 }
@@ -143,8 +149,13 @@ PHP_FUNCTION(dns_check_record)
 PHP_FUNCTION(dns_get_record)
 {
 	char *hostname;
+#if PHP_MAJOR_VERSION >= 7
 	size_t hostname_len;
 	zend_long type_param = PHP_DNS_ANY;
+#else
+	int hostname_len;
+	long type_param = PHP_DNS_ANY;
+#endif
 	zval *authns = NULL, *addtl = NULL;
 	int type_to_fetch;
 	int dns_errno;
@@ -155,7 +166,7 @@ PHP_FUNCTION(dns_get_record)
 	int type, first_query = 1, store_results = 1;
 	zend_bool raw = 0;
 
-	if (zend_parse_parameters(ZEND_NUM_ARGS(), "s|lz!z!b",
+	if (zend_parse_parameters(ZEND_NUM_ARGS() TSRMLS_CC, "s|lz!z!b",
 			&hostname, &hostname_len, &type_param, &authns, &addtl, &raw) == FAILURE) {
 		return;
 	}
@@ -173,7 +184,7 @@ PHP_FUNCTION(dns_get_record)
 		}
 	}
 
-	php_error_docref(NULL, E_WARNING, "dns_get_record() always returns an empty array in PHP.wasm.");
+	php_error_docref(NULL TSRMLS_CC, E_WARNING, "dns_get_record() always returns an empty array in PHP.wasm.");
 
 	/* Initialize the return array */
 	array_init(return_value);
@@ -186,7 +197,11 @@ PHP_FUNCTION(dns_get_record)
 PHP_FUNCTION(dns_get_mx)
 {
 	char *hostname;
+#if PHP_MAJOR_VERSION >= 7
 	size_t hostname_len;
+#else
+	int hostname_len;
+#endif
 	zval *mx_list, *weight_list = NULL;
 	int count, qdc;
 	u_short type, weight;
@@ -196,12 +211,18 @@ PHP_FUNCTION(dns_get_mx)
 	uint8_t *cp, *end;
 	int i;
 
+#if PHP_MAJOR_VERSION >= 7
 	ZEND_PARSE_PARAMETERS_START(2, 3)
 		Z_PARAM_STRING(hostname, hostname_len)
 		Z_PARAM_ZVAL(mx_list)
 		Z_PARAM_OPTIONAL
 		Z_PARAM_ZVAL(weight_list)
 	ZEND_PARSE_PARAMETERS_END();
+#else
+	if (zend_parse_parameters(ZEND_NUM_ARGS() TSRMLS_CC, "sz|z", &hostname, &hostname_len, &mx_list, &weight_list) == FAILURE) {
+		return;
+	}
+#endif
 
 	array_init(mx_list);
 	if (!mx_list) {
@@ -215,7 +236,7 @@ PHP_FUNCTION(dns_get_mx)
 		}
 	}
 
-	php_error_docref(NULL, E_WARNING, "dns_get_mx() always returns an empty array in PHP.wasm.");
+	php_error_docref(NULL TSRMLS_CC, E_WARNING, "dns_get_mx() always returns an empty array in PHP.wasm.");
 
     RETURN_FALSE;
 }
diff --git a/packages/php-wasm/compile/php-wasm-memory-storage/wasm_memory_storage.c b/packages/php-wasm/compile/php-wasm-memory-storage/wasm_memory_storage.c
index f38661df318..1379168f33c 100644
--- a/packages/php-wasm/compile/php-wasm-memory-storage/wasm_memory_storage.c
+++ b/packages/php-wasm/compile/php-wasm-memory-storage/wasm_memory_storage.c
@@ -22,6 +22,8 @@
 #include "Zend/zend_alloc.h"
 #include "php_wasm_memory_storage.h"
 
+#if PHP_MAJOR_VERSION >= 7
+
 /**
  * Allocate a chunk of memory.
  *
@@ -112,6 +114,22 @@ PHP_MSHUTDOWN_FUNCTION(wasm_memory_storage)
 	return SUCCESS;
 }
 
+#else /* PHP < 7 */
+
+/* Custom memory storage is not available in PHP 5.x.
+ * Provide no-op MINIT/MSHUTDOWN. */
+PHP_MINIT_FUNCTION(wasm_memory_storage)
+{
+	return SUCCESS;
+}
+
+PHP_MSHUTDOWN_FUNCTION(wasm_memory_storage)
+{
+	return SUCCESS;
+}
+
+#endif /* PHP_MAJOR_VERSION >= 7 */
+
 /* {{{ PHP_MINFO_FUNCTION */
 PHP_MINFO_FUNCTION(wasm_memory_storage)
 {
diff --git a/packages/php-wasm/compile/php/Dockerfile b/packages/php-wasm/compile/php/Dockerfile
index b7840ef0413..8aa7f6086a3 100644
--- a/packages/php-wasm/compile/php/Dockerfile
+++ b/packages/php-wasm/compile/php/Dockerfile
@@ -289,14 +289,16 @@ RUN cd /root && \
 	git apply --no-index /root/php${PHP_VERSION:0:3}*.patch -v && \
 	chmod +x /root/apply-mysqlnd-patch.sh && \
 	/root/apply-mysqlnd-patch.sh && \
-	if [[ "${PHP_VERSION:0:3}" < '8.3' ]]; then \
-		git apply --no-index /root/php-chunk-alloc-zend-assert-up-to-8.2.patch -v; \
-	elif [[ "${PHP_VERSION:0:3}" == '8.3' ]]; then \
-		git apply --no-index /root/php-chunk-alloc-zend-assert-8.3.patch -v; \
-	elif [[ "${PHP_VERSION:0:3}" == '8.4' ]]; then \
-		git apply --no-index /root/php-chunk-alloc-zend-assert-8.4.patch -v; \
-	elif [[ "${PHP_VERSION:0:3}" == '8.5' ]]; then \
-		git apply --no-index /root/php-chunk-alloc-zend-assert-8.5.patch -v; \
+	if [[ "${PHP_VERSION:0:1}" -ge "7" ]]; then \
+		if [[ "${PHP_VERSION:0:3}" < '8.3' ]]; then \
+			git apply --no-index /root/php-chunk-alloc-zend-assert-up-to-8.2.patch -v; \
+		elif [[ "${PHP_VERSION:0:3}" == '8.3' ]]; then \
+			git apply --no-index /root/php-chunk-alloc-zend-assert-8.3.patch -v; \
+		elif [[ "${PHP_VERSION:0:3}" == '8.4' ]]; then \
+			git apply --no-index /root/php-chunk-alloc-zend-assert-8.4.patch -v; \
+		elif [[ "${PHP_VERSION:0:3}" == '8.5' ]]; then \
+			git apply --no-index /root/php-chunk-alloc-zend-assert-8.5.patch -v; \
+		fi; \
 	fi && \
 	touch php-src/patched
 
@@ -308,7 +310,9 @@ RUN if [ "$WITH_MYSQL" = "yes" ]; then \
 
 # Download and prepare imagick extension if needed (PHP 7.4+)
 # Use version 3.7.0 for PHP 7.x, master for PHP 8.x
-RUN 	if [ "${PHP_VERSION:0:1}" -eq "7" ]; then \
+# Skip entirely for PHP 5.x (imagick 3.7+ requires PHP 7+)
+RUN if [ "${PHP_VERSION:0:1}" -ge "7" ]; then \
+		if [ "${PHP_VERSION:0:1}" -eq "7" ]; then \
 			IMAGICK_BRANCH="3.7.0"; \
 		else \
 			IMAGICK_BRANCH="master"; \
@@ -330,13 +334,22 @@ RUN 	if [ "${PHP_VERSION:0:1}" -eq "7" ]; then \
 			./buildconf --force; \
 		fi && \
 		echo -n ' --with-imagick=/root/lib --with-imagick-config=/root/lib/bin/wasm32-unknown-emscripten-MagickWand-config ' >> /root/.php-configure-flags && \
-		echo -n ' /root/lib/lib/libMagickWand-7.Q16HDRI.a /root/lib/lib/libMagickCore-7.Q16HDRI.a ' >> /root/.emcc-php-wasm-sources
+		echo -n ' /root/lib/lib/libMagickWand-7.Q16HDRI.a /root/lib/lib/libMagickCore-7.Q16HDRI.a ' >> /root/.emcc-php-wasm-sources; \
+	fi
 
 # Disable phar.php generation for all builds (WASM binaries can't execute during build)
 # This must run after buildconf but before configure
 RUN /root/replace.sh 's/pharcmd=pharcmd/pharcmd=/g' /root/php-src/configure && \
 	/root/replace.sh 's/pharcmd_install=install-pharcmd/pharcmd_install=/g' /root/php-src/configure
 
+# Fibers are a PHP 8.1+ feature. They are compiled as a custom assembly
+# implementation by default. However, that implementation does not work with
+# emscripten. The line below disables it for PHP 8.1+.
+# See https://github.com/WordPress/wordpress-playground/issues/92
+RUN if [[ "${PHP_VERSION:0:1}" -gt "8" || ( "${PHP_VERSION:0:1}" -eq "8" && "${PHP_VERSION:2:1}" -ge "1" ) ]]; then \
+		echo -n ' --disable-fiber-asm ' >> /root/.php-configure-flags; \
+	fi
+
 # Build the patched PHP
 WORKDIR /root/php-src
 RUN source /root/emsdk/emsdk_env.sh && \
@@ -356,16 +369,8 @@ RUN source /root/emsdk/emsdk_env.sh && \
 	PKG_CONFIG_PATH="/root/lib/lib/pkgconfig:${PKG_CONFIG_PATH}" \
 		emconfigure ./configure \
 		PKG_CONFIG_PATH=$PKG_CONFIG_PATH \
-	# Fibers are a PHP 8.1+ feature. They are compiled as
-	# a custom assembly implementation by default. However,
-	# that implementation does not work with emscripten.
+	# --disable-fiber-asm is added via .php-configure-flags for PHP 8.1+ only
 	#
-	# The line below disables it, forcing PHP to use the
-	# C implementation instead.
-	#
-	# See https://github.com/WordPress/wordpress-playground/issues/92
-	# for more context.
-	--disable-fiber-asm \
 	--enable-phar \
 	# --enable-json for PHP < 8.0:
 	--enable-json      \
@@ -431,10 +436,17 @@ fi;
 RUN echo '#undef HAVE_ASM_GOTO' >> /root/php-src/main/php_config.h;
 RUN echo '#define HAVE_ASM_GOTO 0' >> /root/php-src/main/php_config.h;
 # Disable asm arithmetic.
-RUN /root/replace.sh 's/ZEND_USE_ASM_ARITHMETIC 1/ZEND_USE_ASM_ARITHMETIC 0/g' /root/php-src/Zend/zend_operators.h;
-RUN /root/replace.sh 's/defined\(__GNUC__\)/0/g' /root/php-src/Zend/zend_multiply.h
-RUN /root/replace.sh 's/defined\(__GNUC__\)/0/g' /root/php-src/Zend/zend_cpuinfo.c
-RUN /root/replace.sh 's/defined\(__clang__\)/0/g' /root/php-src/Zend/zend_cpuinfo.c
+# ZEND_USE_ASM_ARITHMETIC was introduced in PHP 7.x, zend_cpuinfo.c in PHP 7.1
+RUN if [ -f /root/php-src/Zend/zend_operators.h ] && grep -q 'ZEND_USE_ASM_ARITHMETIC' /root/php-src/Zend/zend_operators.h; then \
+		/root/replace.sh 's/ZEND_USE_ASM_ARITHMETIC 1/ZEND_USE_ASM_ARITHMETIC 0/g' /root/php-src/Zend/zend_operators.h; \
+	fi
+RUN if [ -f /root/php-src/Zend/zend_multiply.h ]; then \
+		/root/replace.sh 's/defined\(__GNUC__\)/0/g' /root/php-src/Zend/zend_multiply.h; \
+	fi
+RUN if [ -f /root/php-src/Zend/zend_cpuinfo.c ]; then \
+		/root/replace.sh 's/defined\(__GNUC__\)/0/g' /root/php-src/Zend/zend_cpuinfo.c; \
+		/root/replace.sh 's/defined\(__clang__\)/0/g' /root/php-src/Zend/zend_cpuinfo.c; \
+	fi
 # }}}
 
 # With HAVE_UNISTD_H=1 PHP complains about the missing getdtablesize() function
@@ -461,8 +473,11 @@ RUN /root/replace.sh 's/#define VCWD_POPEN.+/#define VCWD_POPEN(command, type) w
 RUN echo 'extern FILE *wasm_popen(const char *cmd, const char *mode);' >> /root/php-src/Zend/zend_virtual_cwd.h
 
 # Provide a custom implementation of the shutdown() function.
-RUN perl -pi.bak -e $'s/(\s+)shutdown\(/$1 wasm_shutdown(/g' /root/php-src/sapi/cli/php_cli_server.c
-RUN perl -pi.bak -e $'s/(\s+)closesocket\(/$1 wasm_close(/g' /root/php-src/sapi/cli/php_cli_server.c
+# php_cli_server.c exists in PHP 5.4+ (built-in server added in 5.4)
+RUN if [ -f /root/php-src/sapi/cli/php_cli_server.c ]; then \
+		perl -pi.bak -e $'s/(\\s+)shutdown\\(/$1 wasm_shutdown(/g' /root/php-src/sapi/cli/php_cli_server.c; \
+		perl -pi.bak -e $'s/(\\s+)closesocket\\(/$1 wasm_close(/g' /root/php-src/sapi/cli/php_cli_server.c; \
+	fi
 
 # Provide custom implementation fo the shutdown() function.
 # This is used by intl ( which links C++ code ) and need C linkage.
diff --git a/packages/php-wasm/compile/php/apply-mysqlnd-patch.sh b/packages/php-wasm/compile/php/apply-mysqlnd-patch.sh
index 50e5c888960..3dc8421ada2 100644
--- a/packages/php-wasm/compile/php/apply-mysqlnd-patch.sh
+++ b/packages/php-wasm/compile/php/apply-mysqlnd-patch.sh
@@ -9,8 +9,8 @@
 TARGET_FILE="php-src/ext/mysqlnd/mysqlnd_connection.c"
 
 if [ ! -f "$TARGET_FILE" ]; then
-    echo "Error: $TARGET_FILE not found"
-    exit 1
+    echo "Skipping mysqlnd patch: $TARGET_FILE not found (may not exist in this PHP version)"
+    exit 0
 fi
 
 if grep -q "effective_host" "$TARGET_FILE"; then
@@ -31,6 +31,7 @@ else
     if [ -f "$TARGET_FILE.bak" ]; then
         mv "$TARGET_FILE.bak" "$TARGET_FILE"
     fi
-    echo "Failed to apply mysqlnd patch to $TARGET_FILE"
-    exit 1
+    echo "Warning: Could not apply mysqlnd patch to $TARGET_FILE (pattern not found, may be a different PHP version)"
+    # Don't fail - older PHP versions have different mysqlnd code
+    exit 0
 fi
diff --git a/packages/php-wasm/compile/php/php5.6.patch b/packages/php-wasm/compile/php/php5.6.patch
new file mode 100644
index 00000000000..6d894bc6b37
--- /dev/null
+++ b/packages/php-wasm/compile/php/php5.6.patch
@@ -0,0 +1,24 @@
+diff --git a/php-src/ext/standard/file.c b/php-src/ext/standard/file.c
+--- a/php-src/ext/standard/file.c
++++ b/php-src/ext/standard/file.c
+@@ -1627,6 +1627,19 @@
+ 			goto safe_to_copy;
+ 			break;
+ 		case 0:
++			// Fix for https://github.com/WordPress/wordpress-playground/issues/54:
++			// Problem: Calling copy() on an empty source file crashes the JavaScript
++			//          runtime.
++			// Solution: Avoid copying empty files. Just create an empty
++			//           destination file and return.
++			if (src_s.sb.st_size == 0) {
++				char *opened_path = NULL;
++				php_stream *stream = php_stream_open_wrapper(dest, "w", REPORT_ERRORS, &opened_path);
++				if (stream) {
++					php_stream_close(stream);
++					return SUCCESS;
++				}
++				return FAILURE;
++			}
+ 			break;
+ 		default: /* failed to stat file, does not exist? */
+ 			return ret;
diff --git a/packages/php-wasm/compile/php/proc_open.c b/packages/php-wasm/compile/php/proc_open.c
index 6cc1d49e718..f5a53f9582f 100644
--- a/packages/php-wasm/compile/php/proc_open.c
+++ b/packages/php-wasm/compile/php/proc_open.c
@@ -34,7 +34,11 @@
 #include "php_globals.h"
 #include "SAPI.h"
 #include "main/php_network.h"
+#if PHP_MAJOR_VERSION >= 7
 #include "zend_smart_string.h"
+#else
+#include "ext/standard/php_smart_str.h"
+#endif
 
 #if HAVE_SYS_WAIT_H
 #include <sys/wait.h>
@@ -52,6 +56,9 @@
 
 static int le_proc_open;
 
+#if PHP_MAJOR_VERSION >= 7
+/* ============ PHP 7+ implementation ============ */
+
 /* {{{ _php_array_to_envp */
 static php_process_env_t _php_array_to_envp(zval *environment, int is_persistent)
 {
@@ -713,3 +720,74 @@ PHP_FUNCTION(proc_open)
 	RETURN_FALSE;
 }
 /* }}} */
+
+#else /* PHP_MAJOR_VERSION < 7 */
+/* ============ PHP 5.x stub implementation ============ */
+/* proc_open and related functions are provided as stubs for PHP 5.x
+ * because process spawning doesn't truly work in WebAssembly anyway.
+ * The functions need to exist to satisfy the linker. */
+
+static void proc_open_rsrc_dtor_legacy(zend_rsrc_list_entry *rsrc TSRMLS_DC)
+{
+	struct php_process_handle *proc = (struct php_process_handle*)rsrc->ptr;
+	if (proc) {
+		if (proc->pipes) {
+			pefree(proc->pipes, proc->is_persistent);
+		}
+		if (proc->command) {
+			pefree(proc->command, proc->is_persistent);
+		}
+		if (proc->env.envarray) {
+			pefree(proc->env.envarray, proc->is_persistent);
+		}
+		if (proc->env.envp) {
+			pefree(proc->env.envp, proc->is_persistent);
+		}
+		pefree(proc, proc->is_persistent);
+	}
+}
+
+PHP_MINIT_FUNCTION(proc_open)
+{
+	le_proc_open = zend_register_list_destructors_ex(
+		proc_open_rsrc_dtor_legacy, NULL, "process", module_number);
+	return SUCCESS;
+}
+
+PHP_FUNCTION(proc_terminate)
+{
+	php_error_docref(NULL TSRMLS_CC, E_WARNING,
+		"proc_terminate is not supported in this WASM build");
+	RETURN_FALSE;
+}
+
+PHP_FUNCTION(proc_close)
+{
+	php_error_docref(NULL TSRMLS_CC, E_WARNING,
+		"proc_close is not supported in this WASM build");
+	RETURN_LONG(-1);
+}
+
+PHP_FUNCTION(proc_get_status)
+{
+	php_error_docref(NULL TSRMLS_CC, E_WARNING,
+		"proc_get_status is not supported in this WASM build");
+	array_init(return_value);
+	add_assoc_string(return_value, "command", "", 1);
+	add_assoc_long(return_value, "pid", 0);
+	add_assoc_bool(return_value, "running", 0);
+	add_assoc_bool(return_value, "signaled", 0);
+	add_assoc_bool(return_value, "stopped", 0);
+	add_assoc_long(return_value, "exitcode", -1);
+	add_assoc_long(return_value, "termsig", 0);
+	add_assoc_long(return_value, "stopsig", 0);
+}
+
+PHP_FUNCTION(proc_open)
+{
+	php_error_docref(NULL TSRMLS_CC, E_WARNING,
+		"proc_open is not fully supported in this WASM build");
+	RETURN_FALSE;
+}
+
+#endif /* PHP_MAJOR_VERSION >= 7 */
diff --git a/packages/php-wasm/compile/php/proc_open.h b/packages/php-wasm/compile/php/proc_open.h
index b1bfd1e7dc5..7add921a60b 100644
--- a/packages/php-wasm/compile/php/proc_open.h
+++ b/packages/php-wasm/compile/php/proc_open.h
@@ -16,6 +16,8 @@
    +----------------------------------------------------------------------+
  */
 
+#include "php.h"
+
 typedef int php_file_descriptor_t;
 typedef pid_t php_process_id_t;
 
@@ -31,7 +33,11 @@ typedef struct _php_process_env {
 struct php_process_handle {
 	php_process_id_t child;
 	int npipes;
+#if PHP_MAJOR_VERSION >= 7
 	zend_resource **pipes;
+#else
+	void **pipes;
+#endif
 	char *command;
 	int is_persistent;
 	php_process_env_t env;
diff --git a/packages/php-wasm/node-builds/5-6/README.md b/packages/php-wasm/node-builds/5-6/README.md
new file mode 100644
index 00000000000..c158f927051
--- /dev/null
+++ b/packages/php-wasm/node-builds/5-6/README.md
@@ -0,0 +1,13 @@
+# @php-wasm/node-5-6
+
+PHP 5.6 WebAssembly binaries for Node.js.
+
+This package provides PHP 5.6 compiled to WebAssembly for use in Node.js environments. It is part of the WordPress Playground project.
+
+## Usage
+
+```js
+import { getPHPLoaderModule } from '@php-wasm/node-5-6';
+
+const phpLoaderModule = await getPHPLoaderModule();
+```
diff --git a/packages/php-wasm/node-builds/5-6/asyncify/php_5_6.js b/packages/php-wasm/node-builds/5-6/asyncify/php_5_6.js
new file mode 100644
index 00000000000..0ee70722905
--- /dev/null
+++ b/packages/php-wasm/node-builds/5-6/asyncify/php_5_6.js
@@ -0,0 +1,10 @@
+// Placeholder – replace with compiled WASM binary.
+// Compile with: node packages/php-wasm/compile/build.js --PLATFORM=node --PHP_VERSION=5.6
+export const dependencyFilename = '';
+export const dependenciesTotalSize = 0;
+export function init(RuntimeName, PHPLoader) {
+	throw new Error(
+		'PHP 5.6 WASM binaries have not been compiled yet. ' +
+			'Run: node packages/php-wasm/compile/build.js --PLATFORM=node --PHP_VERSION=5.6'
+	);
+}
diff --git a/packages/php-wasm/node-builds/5-6/build.js b/packages/php-wasm/node-builds/5-6/build.js
new file mode 100644
index 00000000000..902e42a5cd4
--- /dev/null
+++ b/packages/php-wasm/node-builds/5-6/build.js
@@ -0,0 +1,92 @@
+import esbuild from 'esbuild';
+import fs from 'fs';
+import path from 'path';
+import { fileURLToPath } from 'url';
+
+const __filename = fileURLToPath(import.meta.url);
+const __dirname = path.dirname(__filename);
+const projectRoot = path.resolve(__dirname, '..', '..', '..', '..');
+const packagePath = path.join(projectRoot, 'packages/php-wasm/node-builds/5-6');
+const distPath = path.join(
+	projectRoot,
+	'dist/packages/php-wasm/node-builds/5-6'
+);
+
+try {
+	fs.mkdirSync(distPath, { recursive: true });
+} catch (e) {
+	// Ignore
+}
+
+/**
+ * Plugin to rewrite imports to work from the dist directory.
+ * Dynamic imports need to be preserved as external and paths adjusted.
+ */
+const externalPathPlugin = {
+	name: 'external-path',
+	setup(build) {
+		// Mark PHP loader files as external and rewrite their paths
+		build.onResolve(
+			{ filter: /\.\.\/(?:jspi|asyncify)\/.*\.js$/ },
+			(args) => {
+				const newPath = args.path.replace('../', './');
+				return { path: newPath, external: true };
+			}
+		);
+		// Mark extension .so files as external and rewrite paths
+		build.onResolve(
+			{ filter: /\.\.\/(?:jspi|asyncify)\/extensions\/.*\.so\?url$/ },
+			(args) => {
+				const newPath = args.path.replace('../', './');
+				return { path: newPath, external: true };
+			}
+		);
+	},
+};
+
+async function build() {
+	// CommonJS build
+	await esbuild.build({
+		entryPoints: [`${packagePath}/src/index.ts`],
+		supported: { 'dynamic-import': true },
+		outExtension: { '.js': '.cjs' },
+		outdir: distPath,
+		platform: 'node',
+		assetNames: '[name]',
+		chunkNames: '[name]',
+		logOverride: {
+			'direct-eval': 'silent',
+			'commonjs-variable-in-esm': 'silent',
+		},
+		format: 'cjs',
+		bundle: true,
+		tsconfig: `${packagePath}/tsconfig.json`,
+		external: ['@php-wasm/*', 'wasm-feature-detect'],
+		loader: { '.wasm': 'file', '.so': 'file' },
+		plugins: [externalPathPlugin],
+	});
+
+	// ESM build
+	await esbuild.build({
+		entryPoints: [`${packagePath}/src/index.ts`],
+		outdir: distPath,
+		platform: 'node',
+		assetNames: '[name]',
+		chunkNames: '[name]',
+		logOverride: {
+			'direct-eval': 'silent',
+			'commonjs-variable-in-esm': 'silent',
+		},
+		packages: 'external',
+		bundle: true,
+		tsconfig: `${packagePath}/tsconfig.json`,
+		external: ['@php-wasm/*', 'wasm-feature-detect'],
+		supported: { 'dynamic-import': true, 'top-level-await': true },
+		format: 'esm',
+		loader: { '.wasm': 'file', '.so': 'file' },
+		plugins: [externalPathPlugin],
+	});
+
+	fs.copyFileSync(`${packagePath}/README.md`, `${distPath}/README.md`);
+}
+build();
diff --git a/packages/php-wasm/node-builds/5-6/jspi/php_5_6.js b/packages/php-wasm/node-builds/5-6/jspi/php_5_6.js
new file mode 100644
index 00000000000..5c55e5492a3
--- /dev/null
+++ b/packages/php-wasm/node-builds/5-6/jspi/php_5_6.js
@@ -0,0 +1,10 @@
+// Placeholder – replace with compiled WASM binary.
+// Compile with: node packages/php-wasm/compile/build.js --PLATFORM=node --PHP_VERSION=5.6 --WITH_JSPI=yes
+export const dependencyFilename = '';
+export const dependenciesTotalSize = 0;
+export function init(RuntimeName, PHPLoader) {
+	throw new Error(
+		'PHP 5.6 WASM binaries have not been compiled yet. ' +
+			'Run: node packages/php-wasm/compile/build.js --PLATFORM=node --PHP_VERSION=5.6 --WITH_JSPI=yes'
+	);
+}
diff --git a/packages/php-wasm/node-builds/5-6/package.json b/packages/php-wasm/node-builds/5-6/package.json
new file mode 100644
index 00000000000..1c77b1b0070
--- /dev/null
+++ b/packages/php-wasm/node-builds/5-6/package.json
@@ -0,0 +1,38 @@
+{
+	"name": "@php-wasm/node-5-6",
+	"version": "3.0.53",
+	"description": "PHP 5.6 WebAssembly binaries for node",
+	"repository": {
+		"type": "git",
+		"url": "https://github.com/WordPress/wordpress-playground"
+	},
+	"homepage": "https://developer.wordpress.org/playground",
+	"author": "The WordPress contributors",
+	"contributors": [
+		{
+			"name": "Adam Zielinski",
+			"email": "adam@adamziel.com",
+			"url": "https://github.com/adamziel"
+		}
+	],
+	"exports": {
+		".": {
+			"import": "./index.js",
+			"require": "./index.cjs"
+		},
+		"./package.json": "./package.json"
+	},
+	"publishConfig": {
+		"access": "public",
+		"directory": "../../../../dist/packages/php-wasm/node-builds/5-6"
+	},
+	"type": "module",
+	"main": "./index.cjs",
+	"module": "./index.js",
+	"types": "index.d.ts",
+	"license": "GPL-2.0-or-later",
+	"engines": {
+		"node": ">=20.10.0",
+		"npm": ">=10.2.3"
+	}
+}
diff --git a/packages/php-wasm/node-builds/5-6/project.json b/packages/php-wasm/node-builds/5-6/project.json
new file mode 100644
index 00000000000..ea421361fbd
--- /dev/null
+++ b/packages/php-wasm/node-builds/5-6/project.json
@@ -0,0 +1,61 @@
+{
+	"name": "php-wasm-node-5-6",
+	"$schema": "../../../../node_modules/nx/schemas/project-schema.json",
+	"sourceRoot": "packages/php-wasm/node-builds/5-6/src",
+	"projectType": "library",
+	"implicitDependencies": ["php-wasm-compile"],
+	"targets": {
+		"build": {
+			"executor": "nx:noop",
+			"dependsOn": ["build:copy-assets"]
+		},
+		"build:mkdir": {
+			"executor": "nx:run-commands",
+			"options": {
+				"commands": ["mkdir -p dist/packages/php-wasm/node-builds/5-6"],
+				"parallel": false
+			}
+		},
+		"build:package-json": {
+			"executor": "@wp-playground/nx-extensions:package-json",
+			"options": {
+				"tsConfig": "packages/php-wasm/node-builds/5-6/tsconfig.lib.json",
+				"outputPath": "dist/packages/php-wasm/node-builds/5-6",
+				"buildTarget": "php-wasm-node-5-6:build:bundle:production"
+			},
+			"dependsOn": ["build:mkdir"]
+		},
+		"build:bundle": {
+			"executor": "nx:run-commands",
+			"options": {
+				"command": "node packages/php-wasm/node-builds/5-6/build.js",
+				"parallel": false
+			},
+			"dependsOn": ["build:mkdir"]
+		},
+		"build:copy-assets": {
+			"executor": "nx:run-commands",
+			"options": {
+				"commands": [
+					"cp -rf packages/php-wasm/node-builds/5-6/jspi dist/packages/php-wasm/node-builds/5-6/",
+					"cp -rf packages/php-wasm/node-builds/5-6/asyncify dist/packages/php-wasm/node-builds/5-6/"
+				],
+				"parallel": false
+			},
+			"dependsOn": ["build:package-json"]
+		},
+		"publish": {
+			"executor": "nx:run-commands",
+			"options": {
+				"command": "node tools/scripts/publish.mjs php-wasm-node-5-6 {args.ver} {args.tag}",
+				"parallel": false
+			},
+			"dependsOn": ["build"]
+		},
+		"package-for-self-hosting": {
+			"executor": "@wp-playground/nx-extensions:package-for-self-hosting",
+			"dependsOn": ["build"]
+		}
+	},
+	"tags": ["scope:php-binaries"]
+}
diff --git a/packages/php-wasm/node-builds/5-6/src/index.ts b/packages/php-wasm/node-builds/5-6/src/index.ts
new file mode 100644
index 00000000000..6786b7ff084
--- /dev/null
+++ b/packages/php-wasm/node-builds/5-6/src/index.ts
@@ -0,0 +1,14 @@
+import type { PHPLoaderModule } from '@php-wasm/universal';
+import { jspi } from 'wasm-feature-detect';
+
+export async function getPHPLoaderModule(): Promise<PHPLoaderModule> {
+	if (await jspi()) {
+		// @ts-ignore
+		return await import('../jspi/php_5_6.js');
+	} else {
+		// @ts-ignore
+		return await import('../asyncify/php_5_6.js');
+	}
+}
+
+export { jspi };
diff --git a/packages/php-wasm/node-builds/5-6/tsconfig.json b/packages/php-wasm/node-builds/5-6/tsconfig.json
new file mode 100644
index 00000000000..b943cbfe62a
--- /dev/null
+++ b/packages/php-wasm/node-builds/5-6/tsconfig.json
@@ -0,0 +1,16 @@
+{
+	"extends": "../../../../tsconfig.base.json",
+	"compilerOptions": {
+		"module": "ESNext",
+		"moduleResolution": "bundler",
+		"allowJs": true,
+		"checkJs": false
+	},
+	"files": [],
+	"include": [],
+	"references": [
+		{
+			"path": "./tsconfig.lib.json"
+		}
+	]
+}
diff --git a/packages/php-wasm/node-builds/5-6/tsconfig.lib.json b/packages/php-wasm/node-builds/5-6/tsconfig.lib.json
new file mode 100644
index 00000000000..71adff9b5c9
--- /dev/null
+++ b/packages/php-wasm/node-builds/5-6/tsconfig.lib.json
@@ -0,0 +1,10 @@
+{
+	"extends": "./tsconfig.json",
+	"compilerOptions": {
+		"outDir": "../../../../dist/packages/php-wasm/node-builds/5-6",
+		"declaration": true,
+		"types": ["node"]
+	},
+	"include": ["src/**/*.ts"],
+	"exclude": ["**/*.spec.ts", "**/*.test.ts"]
+}
diff --git a/packages/php-wasm/node/project.json b/packages/php-wasm/node/project.json
index e51d872f2ed..572d1de8c97 100644
--- a/packages/php-wasm/node/project.json
+++ b/packages/php-wasm/node/project.json
@@ -366,6 +366,14 @@
 				"testNamePattern": "Memcached Network Integration"
 			}
 		},
+		"test-legacy-php": {
+			"executor": "@nx/vitest:test",
+			"outputs": ["{workspaceRoot}/coverage/packages/php-wasm/node"],
+			"options": {
+				"reportsDirectory": "../../../coverage/packages/php-wasm/node",
+				"testFiles": ["legacy-php-versions.spec.ts"]
+			}
+		},
 		"lint": {
 			"executor": "@nx/eslint:lint",
 			"outputs": ["{options.outputFile}"],
diff --git a/packages/php-wasm/node/src/lib/get-php-loader-module.ts b/packages/php-wasm/node/src/lib/get-php-loader-module.ts
index 7c736466072..526a0ee081c 100644
--- a/packages/php-wasm/node/src/lib/get-php-loader-module.ts
+++ b/packages/php-wasm/node/src/lib/get-php-loader-module.ts
@@ -1,5 +1,9 @@
 import { LatestSupportedPHPVersion } from '@php-wasm/universal';
-import type { PHPLoaderModule, SupportedPHPVersion } from '@php-wasm/universal';
+import type {
+	LegacyPHPVersion,
+	PHPLoaderModule,
+	SupportedPHPVersion,
+} from '@php-wasm/universal';
 
 /**
  * Loads the PHP loader module for the given PHP version.
@@ -14,7 +18,7 @@ import type { PHPLoaderModule, SupportedPHPVersion } from '@php-wasm/universal';
  * @returns The PHP loader module.
  */
 export async function getPHPLoaderModule(
-	version: SupportedPHPVersion | string = LatestSupportedPHPVersion
+	version: SupportedPHPVersion | LegacyPHPVersion = LatestSupportedPHPVersion
 ): Promise<PHPLoaderModule> {
 	try {
 		switch (version) {
@@ -53,6 +57,11 @@ export async function getPHPLoaderModule(
 				return (
 					await import('@php-wasm/node-7-4')
 				).getPHPLoaderModule();
+			case '5.6':
+				// @ts-ignore
+				return (
+					await import('@php-wasm/node-5-6')
+				).getPHPLoaderModule();
 		}
 
 		throw new Error(`Unsupported PHP version ${version}`);
diff --git a/packages/php-wasm/node/src/lib/load-runtime.ts b/packages/php-wasm/node/src/lib/load-runtime.ts
index 4d29f6c8c3b..76cb6020598 100644
--- a/packages/php-wasm/node/src/lib/load-runtime.ts
+++ b/packages/php-wasm/node/src/lib/load-runtime.ts
@@ -1,4 +1,5 @@
 import type {
+	LegacyPHPVersion,
 	SupportedPHPVersion,
 	EmscriptenOptions,
 	PHPRuntime,
@@ -87,7 +88,7 @@ export type PHPLoaderOptionsForNode = PHPLoaderOptions & {
  * @see load
  */
 export async function loadNodeRuntime(
-	phpVersion: SupportedPHPVersion,
+	phpVersion: SupportedPHPVersion | LegacyPHPVersion,
 	options: PHPLoaderOptionsForNode = {}
 ) {
 	// TODO: Throw an error if a file lock manager is provided but not a process ID.
@@ -233,24 +234,29 @@ export async function loadNodeRuntime(
 		},
 	};
 
+	// Extensions are only available for modern PHP versions.
+	const modernVersion = phpVersion as SupportedPHPVersion;
 	if (options?.withXdebug === true) {
 		emscriptenOptions = await withXdebug(
-			phpVersion,
+			modernVersion,
 			emscriptenOptions,
 			options.xdebug
 		);
 	}
 
 	if (options?.withIntl === true) {
-		emscriptenOptions = await withIntl(phpVersion, emscriptenOptions);
+		emscriptenOptions = await withIntl(modernVersion, emscriptenOptions);
 	}
 
 	if (options?.withRedis === true) {
-		emscriptenOptions = await withRedis(phpVersion, emscriptenOptions);
+		emscriptenOptions = await withRedis(modernVersion, emscriptenOptions);
 	}
 
 	if (options?.withMemcached === true) {
-		emscriptenOptions = await withMemcached(phpVersion, emscriptenOptions);
+		emscriptenOptions = await withMemcached(
+			modernVersion,
+			emscriptenOptions
+		);
 	}
 
 	emscriptenOptions = await withNetworking(emscriptenOptions);
diff --git a/packages/php-wasm/node/src/test/legacy-php-versions.spec.ts b/packages/php-wasm/node/src/test/legacy-php-versions.spec.ts
new file mode 100644
index 00000000000..096e18cb947
--- /dev/null
+++ b/packages/php-wasm/node/src/test/legacy-php-versions.spec.ts
@@ -0,0 +1,213 @@
+/**
+ * Test suite for legacy PHP versions (5.6).
+ *
+ * This is a SEPARATE test suite from the main PHP 7.4-8.5 tests.
+ * It tests basic functionality for legacy PHP versions that have
+ * been compiled to WebAssembly for WordPress Playground.
+ *
+ * Run independently with:
+ *   npx nx run php-wasm-node:test-legacy-php
+ */
+import { existsSync } from 'fs';
+import { resolve } from 'path';
+import { spawn } from 'child_process';
+import { PHP, setPhpIniEntries } from '@php-wasm/universal';
+import { loadNodeRuntime } from '../lib';
+
+const legacyVersions = ['5.6'] as const;
+
+const nodeBuildsRoot = resolve(__dirname, '../../../node-builds');
+
+/**
+ * Check if a legacy PHP version has binaries available by looking
+ * for the build directory on disk, without spinning up a PHP instance.
+ */
+function isVersionBuilt(version: string): boolean {
+	const dirName = version.replace('.', '-');
+	const buildDir = resolve(nodeBuildsRoot, dirName, 'asyncify');
+	return existsSync(buildDir);
+}
+
+describe('Legacy PHP versions (5.x)', () => {
+	it('detects legacy version availability', () => {
+		const available = legacyVersions.filter(isVersionBuilt);
+		// This test documents which legacy versions have binaries.
+		// When no binaries are compiled, all functional tests are
+		// skipped via it.skipIf(!available).
+		expect(available.length).toBeGreaterThanOrEqual(0);
+	});
+
+	describe.each(legacyVersions)('PHP %s', (phpVersion) => {
+		const available = isVersionBuilt(phpVersion);
+		let php: PHP;
+
+		beforeEach(async () => {
+			if (!available) {
+				return;
+			}
+			php = new PHP(await loadNodeRuntime(phpVersion));
+			php.setSpawnHandler(spawn as any);
+			await setPhpIniEntries(php, {
+				disable_functions: '',
+				html_errors: false,
+			});
+		});
+
+		afterEach(() => {
+			if (available && php) {
+				php.exit();
+			}
+		});
+
+		it.skipIf(!available)('reports correct PHP version', async () => {
+			const result = await php.run({
+				code: '<?php echo PHP_MAJOR_VERSION . "." . PHP_MINOR_VERSION;',
+			});
+			expect(result.text).toBe(phpVersion);
+		});
+
+		it.skipIf(!available)('basic execution: echo Hello World', async () => {
+			const result = await php.run({
+				code: '<?php echo "Hello World";',
+			});
+			expect(result.text).toBe('Hello World');
+		});
+
+		it.skipIf(!available)(
+			'file I/O: file_put_contents and file_get_contents',
+			async () => {
+				const result = await php.run({
+					code: `<?php
+					file_put_contents('/tmp/legacy_test.txt', 'legacy php');
+					echo file_get_contents('/tmp/legacy_test.txt');
+				`,
+				});
+				expect(result.text).toBe('legacy php');
+			}
+		);
+
+		it.skipIf(!available)(
+			'networking: gethostbyname does not crash',
+			async () => {
+				const result = await php.run({
+					code: `<?php
+					$result = gethostbyname('localhost');
+					echo is_string($result) ? 'ok' : 'fail';
+				`,
+				});
+				expect(result.text).toBe('ok');
+			}
+		);
+
+		it.skipIf(!available)('proc_open: basic process spawning', async () => {
+			const result = await php.run({
+				code: `<?php
+					$desc = array(
+						1 => array("pipe", "w"),
+						2 => array("pipe", "w")
+					);
+					$proc = proc_open("echo hello", $desc, $pipes);
+					if (!is_resource($proc)) {
+						echo 'not_supported';
+					} else {
+						$stdout = stream_get_contents($pipes[1]);
+						proc_close($proc);
+						echo trim($stdout);
+					}
+				`,
+			});
+			// PHP 5.x uses stubs that return false;
+			// PHP 7+ has full proc_open support.
+			expect(['hello', 'not_supported']).toContain(result.text);
+		});
+
+		it.skipIf(!available)(
+			'SQLite: CREATE TABLE, INSERT, SELECT',
+			async () => {
+				const result = await php.run({
+					code: `<?php
+					$db = new SQLite3(':memory:');
+					$db->exec('CREATE TABLE t (id INTEGER PRIMARY KEY, name TEXT)');
+					$db->exec("INSERT INTO t (name) VALUES ('Alice')");
+					$row = $db->querySingle("SELECT name FROM t WHERE id = 1");
+					echo $row;
+					$db->close();
+				`,
+				});
+				expect(result.text).toBe('Alice');
+			}
+		);
+
+		it.skipIf(!available)('JSON: json_encode and json_decode', async () => {
+			const result = await php.run({
+				code: `<?php
+					$data = array('key' => 'value', 'num' => 42);
+					$json = json_encode($data);
+					$decoded = json_decode($json, true);
+					echo $decoded['key'] . ':' . $decoded['num'];
+				`,
+			});
+			expect(result.text).toBe('value:42');
+		});
+
+		it.skipIf(!available)('session: session_start', async () => {
+			const result = await php.run({
+				code: `<?php
+					session_start();
+					$_SESSION['test'] = 'legacy';
+					echo $_SESSION['test'];
+				`,
+			});
+			expect(result.text).toBe('legacy');
+		});
+
+		it.skipIf(!available)('strings: mbstring functions', async () => {
+			const result = await php.run({
+				code: `<?php
+					echo mb_strtoupper('hello') . ':' . mb_strlen('test');
+				`,
+			});
+			expect(result.text).toBe('HELLO:4');
+		});
+
+		it.skipIf(!available)('error handling: set_error_handler', async () => {
+			const result = await php.run({
+				code: `<?php
+					set_error_handler(function($errno, $errstr) {
+						echo "caught:" . $errstr;
+					});
+					trigger_error("test_error", E_USER_NOTICE);
+				`,
+			});
+			expect(result.text).toBe('caught:test_error');
+		});
+
+		it.skipIf(!available)(
+			'memory: allocate arrays and check memory_get_usage',
+			async () => {
+				const result = await php.run({
+					code: `<?php
+					$before = memory_get_usage();
+					$arr = array_fill(0, 10000, 'x');
+					$after = memory_get_usage();
+					echo ($after > $before) ? 'allocated' : 'failed';
+				`,
+				});
+				expect(result.text).toBe('allocated');
+			}
+		);
+
+		it.skipIf(!available)('filesystem: mkdir, is_dir, rmdir', async () => {
+			const result = await php.run({
+				code: `<?php
+					mkdir('/tmp/legacy_dir');
+					echo is_dir('/tmp/legacy_dir') ? 'yes' : 'no';
+					rmdir('/tmp/legacy_dir');
+					echo ':';
+					echo is_dir('/tmp/legacy_dir') ? 'yes' : 'no';
+				`,
+			});
+			expect(result.text).toBe('yes:no');
+		});
+	});
+});
diff --git a/packages/php-wasm/supported-php-versions.mjs b/packages/php-wasm/supported-php-versions.mjs
index a4f5973cff3..70c88234c1f 100644
--- a/packages/php-wasm/supported-php-versions.mjs
+++ b/packages/php-wasm/supported-php-versions.mjs
@@ -6,7 +6,7 @@
  * @property {string} lastRelease
  */
 
-export const lastRefreshed = "2026-01-26T23:16:15.020Z";
+export const lastRefreshed = '2026-01-26T23:16:15.020Z';
 
 /**
  * @type {PhpVersion[]}
@@ -54,5 +54,11 @@ export const phpVersions = [
 		loaderFilename: 'php_7_4.js',
 		wasmFilename: 'php_7_4.wasm',
 		lastRelease: '7.4.33',
-	}
+	},
+	{
+		version: '5.6',
+		loaderFilename: 'php_5_6.js',
+		wasmFilename: 'php_5_6.wasm',
+		lastRelease: '5.6.40',
+	},
 ];
diff --git a/packages/php-wasm/universal/src/lib/index.ts b/packages/php-wasm/universal/src/lib/index.ts
index 19235eb511d..51f164d8677 100644
--- a/packages/php-wasm/universal/src/lib/index.ts
+++ b/packages/php-wasm/universal/src/lib/index.ts
@@ -47,10 +47,14 @@ export type { PHPResponseData } from './php-response';
 export type { ErrnoError } from './rethrow-file-system-error';
 export {
 	LatestSupportedPHPVersion,
+	LegacyPHPVersions,
 	SupportedPHPVersions,
 	SupportedPHPVersionsList,
 } from './supported-php-versions';
-export type { SupportedPHPVersion } from './supported-php-versions';
+export type {
+	LegacyPHPVersion,
+	SupportedPHPVersion,
+} from './supported-php-versions';
 export { PHP, __private__dont__use, PHPExecutionFailureError } from './php';
 export type { MountHandler, UnmountFunction } from './php';
 export { loadPHPRuntime, popLoadedRuntime } from './load-php-runtime';
diff --git a/packages/php-wasm/universal/src/lib/supported-php-versions.ts b/packages/php-wasm/universal/src/lib/supported-php-versions.ts
index 64050475b1c..61f42b04488 100644
--- a/packages/php-wasm/universal/src/lib/supported-php-versions.ts
+++ b/packages/php-wasm/universal/src/lib/supported-php-versions.ts
@@ -10,3 +10,6 @@ export const SupportedPHPVersions = [
 export const LatestSupportedPHPVersion = SupportedPHPVersions[0];
 export const SupportedPHPVersionsList = SupportedPHPVersions as any as string[];
 export type SupportedPHPVersion = (typeof SupportedPHPVersions)[number];
+
+export const LegacyPHPVersions = ['5.6'] as const;
+export type LegacyPHPVersion = (typeof LegacyPHPVersions)[number];
diff --git a/packages/php-wasm/web-builds/5-6/README.md b/packages/php-wasm/web-builds/5-6/README.md
new file mode 100644
index 00000000000..7decf92ebe2
--- /dev/null
+++ b/packages/php-wasm/web-builds/5-6/README.md
@@ -0,0 +1,13 @@
+# @php-wasm/web-5-6
+
+PHP 5.6 WebAssembly binaries for the web.
+
+This package provides PHP 5.6 compiled to WebAssembly for use in web browser environments. It is part of the WordPress Playground project.
+
+## Usage
+
+```js
+import { getPHPLoaderModule } from '@php-wasm/web-5-6';
+
+const phpLoaderModule = await getPHPLoaderModule();
+```
diff --git a/packages/php-wasm/web-builds/5-6/asyncify/php_5_6.js b/packages/php-wasm/web-builds/5-6/asyncify/php_5_6.js
new file mode 100644
index 00000000000..8aa9119d702
--- /dev/null
+++ b/packages/php-wasm/web-builds/5-6/asyncify/php_5_6.js
@@ -0,0 +1,10 @@
+// Placeholder – replace with compiled WASM binary.
+// Compile with: node packages/php-wasm/compile/build.js --PLATFORM=web --PHP_VERSION=5.6
+export const dependencyFilename = '';
+export const dependenciesTotalSize = 0;
+export function init(RuntimeName, PHPLoader) {
+	throw new Error(
+		'PHP 5.6 WASM binaries have not been compiled yet. ' +
+			'Run: node packages/php-wasm/compile/build.js --PLATFORM=web --PHP_VERSION=5.6'
+	);
+}
diff --git a/packages/php-wasm/web-builds/5-6/build.js b/packages/php-wasm/web-builds/5-6/build.js
new file mode 100644
index 00000000000..befab4da3c7
--- /dev/null
+++ b/packages/php-wasm/web-builds/5-6/build.js
@@ -0,0 +1,92 @@
+import esbuild from 'esbuild';
+import fs from 'fs';
+import path from 'path';
+import { fileURLToPath } from 'url';
+
+const __filename = fileURLToPath(import.meta.url);
+const __dirname = path.dirname(__filename);
+const projectRoot = path.resolve(__dirname, '..', '..', '..', '..');
+const packagePath = path.join(projectRoot, 'packages/php-wasm/web-builds/5-6');
+const distPath = path.join(
+	projectRoot,
+	'dist/packages/php-wasm/web-builds/5-6'
+);
+
+try {
+	fs.mkdirSync(distPath, { recursive: true });
+} catch (e) {
+	// Ignore
+}
+
+/**
+ * Plugin to rewrite imports to work from the dist directory.
+ * Dynamic imports need to be preserved as external and paths adjusted.
+ */
+const externalPathPlugin = {
+	name: 'external-path',
+	setup(build) {
+		// Mark PHP loader files as external and rewrite their paths
+		build.onResolve(
+			{ filter: /\.\.\/(?:jspi|asyncify)\/.*\.js$/ },
+			(args) => {
+				const newPath = args.path.replace('../', './');
+				return { path: newPath, external: true };
+			}
+		);
+		// Mark extension .so files as external and rewrite paths
+		build.onResolve(
+			{ filter: /\.\.\/(?:jspi|asyncify)\/extensions\/.*\.so\?url$/ },
+			(args) => {
+				const newPath = args.path.replace('../', './');
+				return { path: newPath, external: true };
+			}
+		);
+	},
+};
+
+async function build() {
+	// CommonJS build
+	await esbuild.build({
+		entryPoints: [`${packagePath}/src/index.ts`],
+		supported: { 'dynamic-import': true },
+		outExtension: { '.js': '.cjs' },
+		outdir: distPath,
+		platform: 'browser',
+		assetNames: '[name]',
+		chunkNames: '[name]',
+		logOverride: {
+			'direct-eval': 'silent',
+			'commonjs-variable-in-esm': 'silent',
+		},
+		format: 'cjs',
+		bundle: true,
+		tsconfig: `${packagePath}/tsconfig.json`,
+		external: ['@php-wasm/*', 'wasm-feature-detect'],
+		loader: { '.wasm': 'file', '.so': 'file' },
+		plugins: [externalPathPlugin],
+	});
+
+	// ESM build
+	await esbuild.build({
+		entryPoints: [`${packagePath}/src/index.ts`],
+		outdir: distPath,
+		platform: 'browser',
+		assetNames: '[name]',
+		chunkNames: '[name]',
+		logOverride: {
+			'direct-eval': 'silent',
+			'commonjs-variable-in-esm': 'silent',
+		},
+		packages: 'external',
+		bundle: true,
+		tsconfig: `${packagePath}/tsconfig.json`,
+		external: ['@php-wasm/*', 'wasm-feature-detect'],
+		supported: { 'dynamic-import': true, 'top-level-await': true },
+		format: 'esm',
+		loader: { '.wasm': 'file', '.so': 'file' },
+		plugins: [externalPathPlugin],
+	});
+
+	fs.copyFileSync(`${packagePath}/README.md`, `${distPath}/README.md`);
+}
+build();
diff --git a/packages/php-wasm/web-builds/5-6/jspi/php_5_6.js b/packages/php-wasm/web-builds/5-6/jspi/php_5_6.js
new file mode 100644
index 00000000000..2c5d34fcc78
--- /dev/null
+++ b/packages/php-wasm/web-builds/5-6/jspi/php_5_6.js
@@ -0,0 +1,10 @@
+// Placeholder – replace with compiled WASM binary.
+// Compile with: node packages/php-wasm/compile/build.js --PLATFORM=web --PHP_VERSION=5.6 --WITH_JSPI=yes
+export const dependencyFilename = '';
+export const dependenciesTotalSize = 0;
+export function init(RuntimeName, PHPLoader) {
+	throw new Error(
+		'PHP 5.6 WASM binaries have not been compiled yet. ' +
+			'Run: node packages/php-wasm/compile/build.js --PLATFORM=web --PHP_VERSION=5.6 --WITH_JSPI=yes'
+	);
+}
diff --git a/packages/php-wasm/web-builds/5-6/package.json b/packages/php-wasm/web-builds/5-6/package.json
new file mode 100644
index 00000000000..95f581a5d9c
--- /dev/null
+++ b/packages/php-wasm/web-builds/5-6/package.json
@@ -0,0 +1,38 @@
+{
+	"name": "@php-wasm/web-5-6",
+	"version": "3.0.53",
+	"description": "PHP 5.6 WebAssembly binaries for web",
+	"repository": {
+		"type": "git",
+		"url": "https://github.com/WordPress/wordpress-playground"
+	},
+	"homepage": "https://developer.wordpress.org/playground",
+	"author": "The WordPress contributors",
+	"contributors": [
+		{
+			"name": "Adam Zielinski",
+			"email": "adam@adamziel.com",
+			"url": "https://github.com/adamziel"
+		}
+	],
+	"exports": {
+		".": {
+			"import": "./index.js",
+			"require": "./index.cjs"
+		},
+		"./package.json": "./package.json"
+	},
+	"publishConfig": {
+		"access": "public",
+		"directory": "../../../../dist/packages/php-wasm/web-builds/5-6"
+	},
+	"type": "module",
+	"main": "./index.cjs",
+	"module": "./index.js",
+	"types": "index.d.ts",
+	"license": "GPL-2.0-or-later",
+	"engines": {
+		"node": ">=20.10.0",
+		"npm": ">=10.2.3"
+	}
+}
diff --git a/packages/php-wasm/web-builds/5-6/project.json b/packages/php-wasm/web-builds/5-6/project.json
new file mode 100644
index 00000000000..7330bfd425b
--- /dev/null
+++ b/packages/php-wasm/web-builds/5-6/project.json
@@ -0,0 +1,61 @@
+{
+	"name": "php-wasm-web-5-6",
+	"$schema": "../../../../node_modules/nx/schemas/project-schema.json",
+	"sourceRoot": "packages/php-wasm/web-builds/5-6/src",
+	"projectType": "library",
+	"implicitDependencies": ["php-wasm-compile"],
+	"targets": {
+		"build": {
+			"executor": "nx:noop",
+			"dependsOn": ["build:copy-assets"]
+		},
+		"build:mkdir": {
+			"executor": "nx:run-commands",
+			"options": {
+				"commands": ["mkdir -p dist/packages/php-wasm/web-builds/5-6"],
+				"parallel": false
+			}
+		},
+		"build:package-json": {
+			"executor": "@wp-playground/nx-extensions:package-json",
+			"options": {
+				"tsConfig": "packages/php-wasm/web-builds/5-6/tsconfig.lib.json",
+				"outputPath": "dist/packages/php-wasm/web-builds/5-6",
+				"buildTarget": "php-wasm-web-5-6:build:bundle:production"
+			},
+			"dependsOn": ["build:mkdir"]
+		},
+		"build:bundle": {
+			"executor": "nx:run-commands",
+			"options": {
+				"command": "node packages/php-wasm/web-builds/5-6/build.js",
+				"parallel": false
+			},
+			"dependsOn": ["build:mkdir"]
+		},
+		"build:copy-assets": {
+			"executor": "nx:run-commands",
+			"options": {
+				"commands": [
+					"cp -rf packages/php-wasm/web-builds/5-6/jspi dist/packages/php-wasm/web-builds/5-6/",
+					"cp -rf packages/php-wasm/web-builds/5-6/asyncify dist/packages/php-wasm/web-builds/5-6/"
+				],
+				"parallel": false
+			},
+			"dependsOn": ["build:package-json"]
+		},
+		"publish": {
+			"executor": "nx:run-commands",
+			"options": {
+				"command": "node tools/scripts/publish.mjs php-wasm-web-5-6 {args.ver} {args.tag}",
+				"parallel": false
+			},
+			"dependsOn": ["build"]
+		},
+		"package-for-self-hosting": {
+			"executor": "@wp-playground/nx-extensions:package-for-self-hosting",
+			"dependsOn": ["build"]
+		}
+	},
+	"tags": ["scope:php-binaries"]
+}
diff --git a/packages/php-wasm/web-builds/5-6/src/index.ts b/packages/php-wasm/web-builds/5-6/src/index.ts
new file mode 100644
index 00000000000..6786b7ff084
--- /dev/null
+++ b/packages/php-wasm/web-builds/5-6/src/index.ts
@@ -0,0 +1,14 @@
+import type { PHPLoaderModule } from '@php-wasm/universal';
+import { jspi } from 'wasm-feature-detect';
+
+export async function getPHPLoaderModule(): Promise<PHPLoaderModule> {
+	if (await jspi()) {
+		// @ts-ignore
+		return await import('../jspi/php_5_6.js');
+	} else {
+		// @ts-ignore
+		return await import('../asyncify/php_5_6.js');
+	}
+}
+
+export { jspi };
diff --git a/packages/php-wasm/web-builds/5-6/tsconfig.json b/packages/php-wasm/web-builds/5-6/tsconfig.json
new file mode 100644
index 00000000000..b943cbfe62a
--- /dev/null
+++ b/packages/php-wasm/web-builds/5-6/tsconfig.json
@@ -0,0 +1,16 @@
+{
+	"extends": "../../../../tsconfig.base.json",
+	"compilerOptions": {
+		"module": "ESNext",
+		"moduleResolution": "bundler",
+		"allowJs": true,
+		"checkJs": false
+	},
+	"files": [],
+	"include": [],
+	"references": [
+		{
+			"path": "./tsconfig.lib.json"
+		}
+	]
+}
diff --git a/packages/php-wasm/web-builds/5-6/tsconfig.lib.json b/packages/php-wasm/web-builds/5-6/tsconfig.lib.json
new file mode 100644
index 00000000000..67bfeb7b15f
--- /dev/null
+++ b/packages/php-wasm/web-builds/5-6/tsconfig.lib.json
@@ -0,0 +1,10 @@
+{
+	"extends": "./tsconfig.json",
+	"compilerOptions": {
+		"outDir": "../../../../dist/packages/php-wasm/web-builds/5-6",
+		"declaration": true,
+		"types": ["node"]
+	},
+	"include": ["src/**/*.ts"],
+	"exclude": ["**/*.spec.ts", "**/*.test.ts"]
+}
diff --git a/packages/php-wasm/web/src/lib/get-php-loader-module.ts b/packages/php-wasm/web/src/lib/get-php-loader-module.ts
index 6c32e81ec7c..af949488969 100644
--- a/packages/php-wasm/web/src/lib/get-php-loader-module.ts
+++ b/packages/php-wasm/web/src/lib/get-php-loader-module.ts
@@ -1,4 +1,8 @@
-import type { PHPLoaderModule, SupportedPHPVersion } from '@php-wasm/universal';
+import type {
+	LegacyPHPVersion,
+	PHPLoaderModule,
+	SupportedPHPVersion,
+} from '@php-wasm/universal';
 import { LatestSupportedPHPVersion } from '@php-wasm/universal';
 
 /**
@@ -14,7 +18,7 @@ import { LatestSupportedPHPVersion } from '@php-wasm/universal';
  * @returns The PHP loader module.
  */
 export async function getPHPLoaderModule(
-	version: SupportedPHPVersion = LatestSupportedPHPVersion
+	version: SupportedPHPVersion | LegacyPHPVersion = LatestSupportedPHPVersion
 ): Promise<PHPLoaderModule> {
 	switch (version) {
 		case '8.5':
@@ -38,6 +42,9 @@ export async function getPHPLoaderModule(
 		case '7.4':
 			// @ts-ignore
 			return (await import('@php-wasm/web-7-4')).getPHPLoaderModule();
+		case '5.6':
+			// @ts-ignore
+			return (await import('@php-wasm/web-5-6')).getPHPLoaderModule();
 	}
 	throw new Error(`Unsupported PHP version ${version}`);
 }
diff --git a/tsconfig.base.json b/tsconfig.base.json
index d48f6d6c3e3..7905193b441 100644
--- a/tsconfig.base.json
+++ b/tsconfig.base.json
@@ -24,6 +24,9 @@
 			],
 			"@php-wasm/logger": ["packages/php-wasm/logger/src/index.ts"],
 			"@php-wasm/node": ["packages/php-wasm/node/src/index.ts"],
+			"@php-wasm/node-5-6": [
+				"packages/php-wasm/node-builds/5-6/src/index.ts"
+			],
 			"@php-wasm/node-7-2": [
 				"packages/php-wasm/node-builds/7-2/src/index.ts"
 			],
@@ -66,6 +69,9 @@
 			],
 			"@php-wasm/util": ["packages/php-wasm/util/src/index.ts"],
 			"@php-wasm/web": ["packages/php-wasm/web/src/index.ts"],
+			"@php-wasm/web-5-6": [
+				"packages/php-wasm/web-builds/5-6/src/index.ts"
+			],
 			"@php-wasm/web-7-2": [
 				"packages/php-wasm/web-builds/7-2/src/index.ts"
 			],