# PenEcho

> PenEcho is an open-source (AGPL-3.0) AI canvas for your pen. Write, sketch and paste on an endless canvas, and AI turns it into answers, diagrams, notes and working widgets beside your work. It runs as a desktop app for macOS and Windows, from npm (`npm install -g penecho`), or in the browser at https://penecho.ai.

## New in PenEcho 1.4

- **PenEchoLLM suggestions (Smart Assist):** when you pause after writing, PenEchoLLM ranks the most useful next actions, such as Solve, Typeset, Plot graph, Make diagram, Organize as Note or Animate sketch. One tap and the answer lands where you wrote, with the next step already suggested. It learns from the suggestions you choose on your device, and in the Agent composer it suggests requests based on your canvas, files and project. It is free to try every day without an API key; signing in raises the daily allowance.
- **Notes & Cards:** circle any part of the canvas to keep it as a knowledge card (concepts, formulas, worked examples, references) or a work note (ideas, work, meetings, to-dos), with the original handwriting kept on the card. Cards are categorized automatically and collected in the Library, where they can be searched, bookmarked, reviewed and added to other canvases.
- **Feature tour video (2:30):** https://github.com/penecho/penecho/releases/download/v0.1.0/penecho_knowsyou.mp4 — chapters: Smart Assist 0:00, PenEchoLLM 0:16, live and 3D graphs 0:25, Notes & Cards 0:43, Library 0:55, animate a sketch 1:03, diagrams 1:13, simulations 1:23, 3D models 1:32, explain 1:41, made with PenEcho 1:50.

## What PenEcho does

- **Sketch, then ask:** handwriting, equations, text and images on an endless canvas; AI answers in place.
- **Professional diagrams:** architecture, sequence and workflow diagrams with automatic layout, exportable as SVG or PNG.
- **Working widgets:** calculators, quizzes, simulations and prototypes that run on the canvas.
- **Bring your own AI:** PenEcho models with an account, your own OpenAI- or Anthropic-compatible API key, or a signed-in Codex, Claude Code or Kimi CLI.
- **PenEcho MCP server:** Codex, Claude Code, Kimi, Cursor and other MCP clients can draw on canvases you turn on, and read your handwritten feedback on the next turn. Local MCP stays on your computer; Cloud MCP is a separate signed-in connection at https://penecho.ai/mcp.
- **PenEcho Cloud:** private projects, saved revisions and Linked Devices; Echoes is the community gallery of shared canvases and widgets.

## Links

- [Homepage](https://penecho.ai/): product overview, 1.4 tour and FAQ
- [Downloads](https://penecho.ai/downloads.html): desktop apps for macOS and Windows
- [Echoes](https://penecho.ai/community.html): community canvases and widgets
- [Source code and README](https://github.com/penecho/penecho): AGPL-3.0 repository
- [MCP setup guide](https://github.com/penecho/penecho/blob/main/docs/mcp-setup.md): connecting Codex, Claude Code, Kimi and Cursor
- [Changelog](https://github.com/penecho/penecho/blob/main/CHANGELOG.md): release notes

## Optional

- [Sponsors](https://penecho.ai/sponsors.html)
- [Contact](https://penecho.ai/contact.html)
- [Privacy](https://penecho.ai/privacy.html)
- [Terms](https://penecho.ai/terms.html)