Xournal++

penmentor is an AI-assisted mathematics tutor for pen tablets and handwritten work in Xournal++. A keypress sends the page to a configured AI command-line agent such as Claude Code, Codex, or Antigravity; the agent marks the work on the page with colored annotations, circles the first mistake, ticks correct lines, and provides graduated hints rather than directly giving the answer. Users can select part of a problem for an interactive Manim animation, and the tool supports practice prompts such as find-the-error drills and technique identification. The project is designed for Linux on X11 and uses an Xournal++ plugin together with tools including rofi, slop, xdotool, and PyQt6. It is distributed under the MIT license.

PenEcho is an open-source shared canvas for handwriting, equations, diagrams, and spatial context. It reads marks and their spatial relationships on a 20,000 × 20,000 canvas, then places hints, explanations, formulas, plots, diagrams, and other AI-generated drafts beside the original content. Drafts can be moved, resized, copied, accepted, or discarded before becoming part of the canvas ink; users can draw with a stylus or mouse, lasso confirmed ink to move, resize, recolor, or delete it, and send selected content to Typeset without triggering an AI request when editing ordinary ink. The application supports editable sandboxed HTML widgets, professional diagrams, animations, and live-data plugins, which can be refined in place through incremental unified-diff edits rather than full regeneration. It supports up to ten API or CLI connections, including Kimi, MiniMax, Codex, and Claude Code configurations, with a selectable active connection per client. Canvases can be organized into projects, shared across authorized devices, and exported as cropped PNG files. PenEcho provides a desktop app and an npm installation requiring Node.js 20.3 or newer. It can run offline with a user's own API or authenticated CLI setup; API credentials remain on the host device and are not sent to browser code. PenEcho Cloud is an optional companion service for private versioned projects, synchronized favorites, linked-device remote access through a relay, and public sharing of Canvases and Widgets as Echoes or Crafts. The project is supported through Moonshot AI's Kimi Open Source Friends program.

Kool Brushez is a p5.js drawing app with six independent brushes: Score draws flowing musical-staff ribbons, Schematic creates drafting diagrams, Balloon reveals airbrushed shapes, Subway generates branching transit lines, Crowd draws animated people, and Gunpla grows model-kit sprues. All brushes use one shared canvas, so users can switch between them without reloading or losing existing marks; each brush has its own JavaScript drawing algorithm, settings, preview, and registry entry. The app provides brush-specific controls, auto-fill and variation modes, undo and redo, erasing across brushes, aspect-ratio fitting, keyboard shortcuts, touch and pen input, and PNG export. It is built with Vite, plain JavaScript and CSS, and is released under the MIT License.

Quickdraw is an MIT-licensed, open-source infinite-canvas whiteboard SDK for React, React Native/Expo, and plain JavaScript applications. It provides freehand pressure ink, highlighters, shapes, arrows, lines, text, sticky notes, images, selection and transformation tools, laser presentation pointers, themes, grids, palm rejection, and PNG export. Its data model emits JSON-safe diffs for real-time synchronization over an application-chosen transport, with support for persistence, undo/redo, and stroke-by-stroke replay. The project provides separate core, React, and React Native packages; the core is plain ESM with zero runtime dependencies and can run in modern browsers without a build step. The repository states that it is free for commercial use and has no license fee.

DeepTutor is an open-source, self-hostable AI tutoring platform developed by HKUDS for lifelong personalized tutoring. It provides a web application and command-line interface for interactive learning, problem solving, quiz generation, deep research, visualization, and mastery practice, with persistent memory and learning state shared across knowledge bases, books, notebooks, tutor personas, and other activities. The platform supports multi-agent problem solving, retrieval-augmented learning with source-traced and page-level citations, math animations, interactive visualizations, and tutor bots built from personal study materials. Its knowledge sources include personal documents, EPUBs and books with annotations, GitHub repositories, web search, and connected libraries; documented retrieval and ingestion options include GraphRAG, PageIndex, LightRAG, linked knowledge bases, Obsidian, and configurable parsing and vector backends. DeepTutor also includes courses, research workflows, an ecosystem of MCP services and tool or capability plugins, and integrations with connected coding agents and other partners. It can run locally or through Docker.