Marginalia puts AI right in the margins of your reading. Open an ePub or PDF, hit a sentence you want to dig into, select it, and an assistant joins you in the side panel — already holding the context of the book. Explain an allusion, translate a passage, summarize the thread, or just ask — and when you'd rather listen, it reads the page aloud. No breaking your flow, no copy-pasting into another window.
It's local-first, bring-your-own-key, and tied to no single model provider — your books and notes stay quietly on your own machine.
Select text in an ePub or text-layer PDF and a floating toolbar appears: Explain / Translate / Summarize in one click, or hit "Ask AI" for an open question. Answers stream into the side panel, so you can read and ask in the same breath.
Press play and Marginalia reads the book aloud, paragraph by paragraph — highlighting the line it's on and scrolling to keep pace, straight through chapter breaks. Choose a voice per language and set the speed; it speaks with the voices already on your machine, so nothing leaves it.
Every question ships its context as visible, toggleable chips: your exact selection, its surrounding paragraph, the chapter summary, the whole-book summary — each labeled, each switchable. You always know what the AI sees.
Give the assistant a name, a persona, and standing instructions, and it shows up that way in every conversation. It can remember what matters across chats — and every memory is yours to read, edit, or delete, or to switch off entirely. Each book keeps its own saved conversations, so you can return to an old thread or start a fresh one.
Five highlight colors plus underline, with sticky notes on any passage — all gathered into a side-panel list in reading order, one click back to the spot. Each book also gets its own free-form Markdown notebook for the thoughts that don't belong to a single line.
Real, continuously-scrolling reading that remembers and restores your place. ePub gets tuneable typography; PDF gets fit-to-width rendering, zoom controls, clickable links, and text-layer selection when the document provides text. Switch between dark / light / system themes anytime.
An Apple Books-style cover wall to spot your books at a glance. Drag an ePub or PDF into the window to import it; books without a cover get a tasteful generated tile.
Connect OpenAI, Anthropic, Google, or any OpenAI-compatible endpoint (self-hosted gateway or proxy).
A bilingual interface (English / 简体中文) that follows your system language. Everything lives on your machine — no uploads, no account required.
brew tap eurfelux/tap
brew install --cask marginaliaThe cask clears the quarantine flag for you, so the app opens right away — no Gatekeeper hoops.
Grab the latest .dmg from Releases, open it, and drag Marginalia into Applications.
Important
macOS will warn that the app "cannot be verified" on first launch — Marginalia is ad-hoc signed but not notarized by Apple (that requires a paid developer certificate). To open it anyway:
- Double-click the app once (the warning appears) — then go to System Settings → Privacy & Security, scroll down, and click Open Anyway.
- Or, from a terminal:
xattr -d com.apple.quarantine /Applications/marginalia.app
The app is open source — you can always audit the code and build it yourself with pnpm make.
- Drop in a book — drag an ePub or PDF into the library and start reading.
- Select text, hit "Ask AI" — the side panel picks up the passage's context automatically.
- Watch the answer stream in — read, annotate, follow up, and summarize, all in one window.
- Make it yours — give the assistant a name and persona, and let it remember what matters from chat to chat.
- Transparent context — every piece of context sent to the AI is shown and switchable.
- Local-first — books, progress, notes, and conversations stay on your own machine.
- No lock-in — bring your own API key, switch models and providers freely.
GPL-3.0-or-later © 2026 eurfelux