Marginalia

Marginalia: PDF and EPUB reader with an integrated AI that cites exact book passages for every answer.

Marginalia is a PDF and EPUB reader that integrates an AI assistant directly in the margin of the text. Users open files in their browser without installation, and the files never upload entirely to a server. The AI answers questions about the text and provides citations that jump directly to the referenced passages with a single tap. It features a text view that reflows PDFs for mobile screens, preserves formulas and code blocks, and offers light, sepia, or dark themes. It is designed for students, researchers, and professionals who read textbooks, papers, statutes, and manuals.

Marginalia at a glance

Best for: Student, Researcher
Runs on: Web
Pricing: Free
Released: October 2026
Category: AI research tool
Website: marginal-ia.app

Key features

Text view reflows PDFs for mobile screens
AI answers questions with exact passage citations
Highlights in four colors with linked notes
Preserves formulas and code blocks
Generates a table of contents
Provides light, sepia, and dark themes

Use it for

Ask questions about textbooks and technical manuals
Study legal statutes and bar exam materials
Read academic papers on mobile devices without zooming
Highlight text and write notes linked to specific passages

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