InkPrint

Turn your BOOX (or any Android e-ink reader) into a wireless network printer.
Documents printed from any device on your LAN are saved as PDF directly to the BOOX — or, through the InkPrint EPUB printer, as a reflowable e-book.

macOS — print to InkPrint from Chrome	Android app — file received

The story behind InkPrint

InkPrint was inspired by my daughter, Kiki.

To look after her eyes, Kiki does her reading on an e-ink reader. One day she pointed out that if we cared about the environment, we should be wasting less paper — so why not "print" straight to the e-reader instead?

The idea turned out to be simple and practical. Every computer and phone already knows how to print, so printing to an e-ink reader needs no changes to the apps and systems people already use: pick the printer, press Print, and the document lands on the reader instead of on paper. That is how this app came to be.

Thank you, Kiki. 💚

项目缘起

InkPrint 的灵感来自我的女儿 Kiki。

为了保护视力，Kiki 一直用电纸书阅读。有一天她说，为了保护环境，我们应该少浪费一些纸张，那为什么不把要打印的东西直接“打印”到电纸书上呢？

这个想法简单又实用。电脑和手机本来就会打印，打印到电纸书不需要改造任何已有的应用和信息系统：选中打印机，点一下打印，文档就会出现在电纸书上，而不是纸上，既方便又环保。于是就有了这个 App。

谢谢你，Kiki。💚

How it works

macOS / Windows / Linux / iOS / Android
        │  print via IPP over WiFi
        ▼
  InkPrint (Android app on BOOX)
  ├── IPP/HTTP server  (port 6310)
  ├── mDNS/Bonjour advertiser  (_ipp._tcp + AirPrint subtype)
  └── Saves PDF to  /Documents/InkPrint/

IPP 2.0 server implemented in Rust (inkprint-core crate)
AirPrint compatible — macOS, iOS, and iPadOS discover it with zero configuration
Bonjour/mDNS advertisement broadcasts both _ipp._tcp and _universal._sub._ipp._tcp so all major platforms can auto-discover the printer
Pure PDF storage — every print job is saved as a PDF file, ideal for e-ink reading
Rust core compiled to aarch64-linux-android via cargo-ndk, bridged to Kotlin via UniFFI

Requirements

Component	Version
Android (target device)	8.0+ (API 26+)
Android NDK	r29
Android SDK platform	36 (compile & target)
Rust toolchain	nightly
cargo-ndk	latest
JDK	17
macOS build host	Apple Silicon recommended

Build

# Rust .so, UniFFI bindings, pdfium download (checksum-verified), debug APK
make android-debug

# Install on device
adb install -r android/app/build/outputs/apk/full/debug/app-full-debug.apk

The app has two flavors:

Flavor	EPUB printer	Native deps	Build
`full` (Play, GitHub releases)	yes	pdfium (`make fetch-native-deps`), ONNX Runtime (Maven AAR), models in `android/app/src/full/assets/models/`	`make android-release` / `make android-bundle`
`fdroid`	no	none — Rust core built with `--no-default-features`	`make android-fdroid`

Tests: make rust-test runs everything that needs no native libraries; make epub-test (macOS arm64) downloads pdfium and ONNX Runtime and also runs the end-to-end PDF → EPUB conversions.

Note: Use the rustup nightly toolchain (RUSTC=~/.rustup/toolchains/nightly-aarch64-apple-darwin/bin/rustc).
Homebrew's rustc does not include Android targets.

Release build

Google Play accepts an Android App Bundle, not an APK:

make android-bundle   # -> android/app/build/outputs/bundle/fullRelease/app-full-release.aab

Signing credentials are read from Gradle properties or the environment and are never stored in the repository. Put them in ~/.gradle/gradle.properties:

INKPRINT_STORE_FILE=/absolute/path/to/inkprint-release.jks
INKPRINT_STORE_PASSWORD=...
INKPRINT_KEY_ALIAS=inkprint
INKPRINT_KEY_PASSWORD=...

Without them the release build still succeeds, but the output is unsigned.

Privacy

InkPrint collects nothing: no accounts, no analytics, no servers, no outbound connections. Everything stays on the device and the local network — including the EPUB printer's layout analysis and text recognition, whose models ship inside the app.

Privacy policy — English · 中文

Usage

Install the APK on your BOOX (or other android device) device
Open InkPrint and tap Start Printer Service
Add the printer on your computer/phone (see below)
Print — the PDF appears in the app's file list and in Documents/InkPrint/ (or your chosen save folder) on the BOOX

EPUB printer

Next to InkPrint, the app offers a second printer, InkPrint EPUB (ipp://<device>:6310/ipp/epub). Print to it and the BOOX turns the document into a reflowable EPUB in the background — the notification shows the page being converted and has a Cancel button.

Text-layer PDFs (almost anything printed from a computer) are rebuilt from their text: headings, paragraphs, lists, and pictures in reading order. About 0.6 s per page on a BOOX Note Air (Snapdragon 636).
Scanned pages go through on-device OCR (PaddleOCR PP-OCRv6 tiny), about 3 s per page. Switch Recognise scanned pages off to keep them as pictures.
Tables, charts and formulas are kept as pictures (grayscale, cut from the page).
Running headers, footers and page numbers are dropped; paragraphs split by a page break are joined; long documents are split into chapters.

The EPUB replaces the PDF unless Also keep the PDF is on. If a conversion fails or is cancelled, the PDF is saved instead. Turning the EPUB printer off removes it from the network. The F-Droid build does not include it.

Adding the printer

There are two printers: InkPrint saves a PDF, InkPrint EPUB saves a reflowable e-book (/ipp/print and /ipp/epub on port 6310). Add one or both; each platform below covers both.

macOS (AirPrint — recommended)

System Settings → Printers & Scanners → Add Printer, Scanner or Fax…
InkPrint and InkPrint EPUB appear in the list automatically — select one
Use: AirPrint is selected — click Add
Repeat for the other printer if you want both

No driver download needed. Works on macOS Ventura, Sonoma, and Sequoia.

Manual — Terminal (by IP, e.g. over Tailscale/VPN, where auto discovery doesn't work):

lpadmin -p InkPrint -E \
  -v ipp://<ANDROID_IP>:6310/ipp/print \
  -m everywhere

# EPUB printer
lpadmin -p InkPrint-EPUB -E \
  -v ipp://<ANDROID_IP>:6310/ipp/epub \
  -m everywhere

Don't add it with "Generic PostScript Printer": that sends PostScript, and InkPrint only accepts PDF.

Windows 10 / 11

Automatic:

Settings → Bluetooth & devices → Printers & scanners
Click Add device — InkPrint and InkPrint EPUB appear on the same network
Click Add device next to the one you want (or both)

If InkPrint doesn't show up, add it manually:

Manual (add by IP):

Settings → Printers & scanners → Add device
"The printer that I want isn't listed" → Add a printer using an IP address or hostname
Protocol: IPP / Hostname: <ANDROID_IP> / Port: 6310 / Queue: ipp/print (EPUB printer: ipp/epub)
Driver: Microsoft IPP Class Driver
For the EPUB printer, repeat with Queue ipp/epub and name it InkPrint EPUB

Don't pick a "Generic / Text Only" or PostScript driver: those send text or PostScript instead of PDF, and InkPrint rejects the job.

The Windows setup hasn't been verified end-to-end yet. If jobs fail with "document format not supported", please open an issue.

Linux

# Add printer (driverless, IPP Everywhere)
sudo lpadmin -p InkPrint -E \
  -v ipp://<ANDROID_IP>:6310/ipp/print \
  -m everywhere

# EPUB printer
sudo lpadmin -p InkPrint-EPUB -E \
  -v ipp://<ANDROID_IP>:6310/ipp/epub \
  -m everywhere

# Set as default (optional)
sudo lpoptions -d InkPrint

# Print
lp -d InkPrint /path/to/document.pdf

Works on Ubuntu, Debian, Fedora, Arch, and any distro with CUPS.

GNOME / KDE GUI: Settings → Printers → Add a Printer → enter ipp://<ANDROID_IP>:6310/ipp/print (EPUB printer: .../ipp/epub) → driver IPP Everywhere (driverless). Don't pick a Generic, PostScript or vendor driver: those don't send PDF.

iOS / iPadOS — AirPrint, zero config

Connect iPhone/iPad to the same WiFi network as the BOOX(ANDROID)
In any app: Share → Print
Tap Select Printer — InkPrint and InkPrint EPUB appear automatically
Tap Print — InkPrint saves a PDF on the BOOX, InkPrint EPUB an e-book

⚠️ Personal Hotspot limitation: if your iPhone is sharing its hotspot, devices connected to it cannot discover the printer. Use a shared WiFi router.

Android

Built-in Print Service (Android 8+):

Settings → Connected devices → Connection preferences → Printing
Default Print Service → Enable
InkPrint and InkPrint EPUB appear automatically on the same WiFi

Manual:

In Default Print Service, tap ⋮ → Add printer → Add printer by IP address
Enter the address with the port: <ANDROID_IP>:6310

Adding by IP only reaches the PDF printer (Android's dialog takes no printer path); use auto-discovery for InkPrint EPUB.

Printing over Tailscale / VPN / another subnet

Auto discovery uses mDNS (Bonjour), which only works inside one Wi-Fi network — Tailscale and most VPNs don't carry it. You can still print by adding the printer manually with the device's Tailscale/VPN IP (100.x.y.z) using the per-platform Manual steps above. While the service runs, the app lists every address it can be reached at (Wi-Fi, Tailscale, VPN) with a copyable printer URL, and How to add this printer can show its steps for any of them.

The one thing to get right is the driver: InkPrint only stores PDF. Choose the driverless option (-m everywhere on macOS and Linux, Microsoft IPP Class Driver on Windows, <IP>:6310 in Android's Default Print Service). Generic PostScript, text-only or vendor drivers send other formats; InkPrint rejects those jobs with "document format not supported" instead of saving a file that won't open.

Upgrading: re-add the printer

Older versions advertised PWG raster and JPEG support without actually accepting them, so a printer added with an older version can still send those formats (on macOS, for example, printing a JPEG fails with "the printer cannot print the supplied content"). After upgrading, remove InkPrint from your computer's printer list and add it again.

Where the files are

Tap Choose under Printed Files to pick a save folder (the picker opens at Documents/InkPrint/). Received PDFs are then moved straight into that folder, and the app lets you browse it: open subfolders, create folders, and share, rename, move or delete files — the same files your reader app sees.

Until a folder is chosen, every received PDF is saved twice on the device:

Documents/InkPrint/ — shared folder, visible to readers and file managers
Android/data/com.inkprint.app/files/InkPrint/ — the app's own copy (moved into the save folder once you pick one)

Project structure

inkprint/
├── inkprint-core/          # Rust library
│   ├── src/
│   │   ├── lib.rs          # UniFFI entry point, public API
│   │   ├── ipp/            # IPP protocol: parser, types, operations, printer state
│   │   ├── server/         # HTTP server (hyper 1.x) + TCP listener
│   │   └── mdns/           # mDNS advertiser (mdns-sd, pure Rust)
│   ├── inkprint.udl        # UniFFI interface definition
│   └── Cargo.toml
├── inkprint-epub/          # PDF → EPUB: pdfium, layout + OCR (oar-ocr / ONNX Runtime), EPUB writer
├── design/                 # Design notes (epub-export.md)
├── spikes/ocr-bench/       # On-device OCR benchmark used for performance regressions
├── android/                # Android app
│   └── app/src/main/
│       ├── kotlin/com/inkprint/app/
│       │   ├── MainActivity.kt     # Compose UI
│       │   ├── PrinterService.kt   # Foreground service
│       │   ├── ConversionQueue.kt  # Background PDF → EPUB conversion
│       │   ├── BootReceiver.kt     # Auto-start on boot
│       │   └── InkPrintLib.kt      # UniFFI wrapper
│       └── jniLibs/arm64-v8a/     # Compiled .so files
├── Makefile
└── README.md

Architecture notes

Port 6310 — Android blocks ports below 1024 for non-system apps; 631 (standard IPP) is not usable
mDNS from Rust — Android's NsdManager API (< API 33) cannot register _universal._sub._ipp._tcp subtypes required for AirPrint auto-selection. The Rust mdns-sd crate advertises both _ipp._tcp and _universal._sub._ipp._tcp correctly
PDF-only storage — the cupsFilter2 PPD directive and IPP document-format-accepted list guide clients to send PDF; raw PostScript is accepted and stored but not rendered
UniFFI bridge — Rust callbacks (PrintJobCallback) are implemented in Kotlin and called from the IPP job handler when a file is fully received
Two printers, one port — /ipp/print (PDF) and /ipp/epub (EPUB) differ in name, UUID and output; the job callback tells Kotlin which one received the file
EPUB conversion — inkprint-epub loads libpdfium.so and libonnxruntime.so at runtime (pdfium-render binding, ort load-dynamic), so the Rust build never links them. See design/epub-export.md

License

If you use InkPrint commercially, please drop a line to xjohn1666@gmail.com — I'd love to hear about it. This is a friendly request, not an extra condition: the MIT license alone governs your rights.

如将 InkPrint 用于商业用途，欢迎发邮件至 xjohn1666@gmail.com 告知。这只是请求，并非附加条件，您的权利仅以 MIT 协议为准。

Name		Name	Last commit message	Last commit date
.cargo		.cargo
android		android
design		design
docs		docs
fastlane/metadata/android		fastlane/metadata/android
inkprint-core		inkprint-core
inkprint-epub		inkprint-epub
scripts		scripts
spikes/ocr-bench		spikes/ocr-bench
uniffi-bindgen		uniffi-bindgen
.gitignore		.gitignore
Cargo.lock		Cargo.lock
Cargo.toml		Cargo.toml
LICENSE		LICENSE
Makefile		Makefile
README.md		README.md
THIRD_PARTY_NOTICES.md		THIRD_PARTY_NOTICES.md
rust-toolchain.toml		rust-toolchain.toml

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InkPrint

The story behind InkPrint

项目缘起

How it works

Requirements

Build

Release build

Privacy

Usage

EPUB printer

Adding the printer

macOS (AirPrint — recommended)

Windows 10 / 11

Linux

iOS / iPadOS — AirPrint, zero config

Android

Printing over Tailscale / VPN / another subnet

Upgrading: re-add the printer

Where the files are

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InkPrint

The story behind InkPrint

项目缘起

How it works

Requirements

Build

Release build

Privacy

Usage

EPUB printer

Adding the printer

macOS (AirPrint — recommended)

Windows 10 / 11

Linux

iOS / iPadOS — AirPrint, zero config

Android

Printing over Tailscale / VPN / another subnet

Upgrading: re-add the printer

Where the files are

Project structure

Architecture notes

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