Tools for Annotating Research PDFs

The problem, in plain words: “I need a reliable way to read research papers in PDF format, highlight passages, and handwrite notes.”

Libritus fits best, with 3 more that fit too.

You want to read research papers as PDFs, highlight passages, and add handwritten notes reliably.

Updated September 2026.

What fits

Libritusstrong · 88

Libritus is built for reading and annotating PDFs, with highlights, notes, and freehand drawings alongside the document.

Best for: Researchers who want PDF text and handwritten-style marks together on a canvas.

Same approach: Goodnotes 86 · Pen and Paper 82 · PaperNote 80

Partly fits

PDF Scholarpartial · 56

A research-focused PDF reader and annotator that is free and works offline unless you ask a question.

Won’t cover: It describes research annotation but does not specify handwritten note support.

Web Highlightspartial · 49

It can highlight, annotate, and save PDFs in a browser, which covers part of your reading workflow.

Won’t cover: It is a browser highlighter rather than a research-focused tool for handwritten PDF notes.

Questions

What's the best tool for Annotating Research PDFs?

Libritus is the strongest match — Libritus is built for reading and annotating PDFs, with highlights, notes, and freehand drawings alongside the document.

Is there a tool that fully solves this?

4 products match this closely.

What won't these tools cover?

It describes research annotation but does not specify handwritten note support. · It is a browser highlighter rather than a research-focused tool for handwritten PDF notes.

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