GoKawiilPenmentor uses Claude, Gemini or GPT to mark handwritten calculus work in Xournal++
Penmentor is a tool that integrates with the Xournal++ note-taking app, letting users press a key while writing math by hand so an AI model (Claude, Gemini or GPT) annotates their work on screen with marks resembling a teacher's corrections. Boxing a specific step, like an integral, can trigger an interactive animation built with 3Blue1Brown's manim library to illustrate the concept.
GoKawiil's interpretation of the reporting above, not reported fact.
The tool targets a specific workflow gap for pen-tablet-based math study, where students previously had to screenshot handwritten work and paste it into chat interfaces to get feedback. By offering hints rather than direct answers and interactive visualizations, it suggests a design philosophy aimed at reinforcing learning rather than just providing solutions, according to the creator's stated rationale.
- Penmentor integrates AI feedback directly into the Xournal++ handwriting workflow via a keyboard shortcut.
- It supports multiple AI backends including Claude, Gemini and GPT, using the user's own subscription.
- Boxed equations can generate interactive manim-based animations in the style of 3Blue1Brown videos.
Wacom Intuos Pen Tablet — If you're marking up handwritten calculus in xournal++ like in this workflow, a Wacom Intuos gives you the natural pen-on-screen feel needed for smooth handwriting input. It's a reliable, widely-used tablet for digital note-taking and math work with styluses, pairing nicely with apps like xournal++ for this kind of annotated practice.
See Wacom Intuos Pen Tablet on Amazon → Affiliate link — we may earn a commission on purchases, at no extra cost to you. Product picked by AI based on this article; it is not a tested recommendation.Source: github.com, 2026-10-20
Published there as: “Show HN: Penmentor – Claude marks up your handwritten math like a teacher”
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