[Web] Marginalia – EPUB/PDF reader; AI answers with verifiable citations to the page

[efolio]

For about a year my way of reading technical books was: read a page, hit something I didn't get, photograph it, paste it into a chat, get an answer, go back to the book. The answers lived in a chat with no connection to the book, I lost them all, and I never knew whether the model was explaining the page or making it up.

That last part is the usual objection to AI in a reader, and it's a fair one. So Marginalia is built around it: the assistant can only answer from the book, and every answer carries citations to the passages it used. Tap one and the reader jumps to that page and highlights the text. If the answer isn't in the book, it says so. You don't have to trust it; you check it, in the book, in one tap.

The other half is that the reader itself is carefully made. It runs in the browser, for EPUB and PDF, and the interface is the margin of the book: the text comes first and everything else stays out of the way.

https://marginal-ia.app/en

What it does

• Reads EPUB and PDF with your typeface, size, spacing, margins, one or two columns, paginated or scrolled, light, sepia or dark.
• PDFs get a text view: a two-column paper or a dense manual reflows like an EPUB at your font size, with figures, tables and code kept in place. The original page is one tap away.
• Highlights in four colors, notes on any of them, a notes panel by chapter, search, table of contents, footnotes in a popover.
• Ask about a word, a paragraph, a code block or a figure, and get an answer with citations that open the page.
• Installable as an app on Android, desktop and iOS.

Where your books live

The book never leaves your browser; only your question and the few passages needed to answer it go to the server. Reading and annotating need no account. The first three questions in any book don't either; after that it's a free account with just an email, which syncs highlights, notes and position across your browsers. The file is never uploaded, so on another device you drop it once and everything is waiting.

What I'd like from you

A PDF that comes out wrong in the text view, and whatever you'd expect from a reader that dback link in the footer, or reply here.

Free, no ads. One person; I'll answer everything in this thread.