PenEcho
Get PenEcho
NewPenEchoLLM and Notes & Cards in 1.4

AI that shows,
not just tells.

Bring a question, a sketch, or your notes. Work it out with AI on the same page.

Get PenEcho Explore Echoes
—GitHub stars —Community forks AGPL-3.0Open-source Canvas Your model.Any API or supported CLI

New in PenEcho 1.4

It knows what you need.

PenEchoLLM reads what you just wrote and suggests the next step. Notes & Cards keep what matters: circle it, and it becomes a card you can find again.

PenEcho 1.4 tour · 2:30 Smart Assist, PenEchoLLM, Notes & Cards, live graphs, simulations and 3D, all on one canvas.

PenEchoLLM suggestions

You write. It knows the next step.

Pause after writing and PenEchoLLM ranks what you need next. One tap, and the answer lands right where you wrote, with the next step already suggested.

  • Solve
  • Typeset
  • Plot graph
  • Make diagram
  • Organize as Note
  • Animate sketch
  • Learns from the suggestions you choose, on your device.
  • Suggests Agent requests from your canvas, files and project.
  • Free to try every day, no API key needed. Sign in for a larger allowance.

Notes & Cards

Circle it. Keep it as a card.

Lasso a formula, a sketch or an answer and PenEcho turns it into a card, with your original handwriting kept on it. Every card is categorized for you and waits in the Library.

  • Knowledge cards for concepts, formulas and worked examples; work notes for ideas, meetings and to-dos.
  • Search, bookmark and review every card in the Library.
  • Bring any card into another canvas and keep building.

Prefer your own agent? Codex, Claude Code and any MCP client can work on the same canvas. See PenEcho MCP

PenEcho MCP server

A spatial extension
of your AI conversation.

Keep talking in Codex, Claude, Kimi, or any MCP-ready agent. PenEcho turns the conversation into diagrams and live previews you can see, mark up, and send back.

CodexClaudeKimiAny MCP client
  1. Talk where you already work.No new chat window. Your agent draws straight onto the canvas.
  2. See it before it’s finished.Explanations become diagrams. Ideas become interactive previews.
  3. Mark it up. Send it back.Circle and annotate by hand — your AI reads it in the next round.
PenEcho Canvas
An architecture discussion with AI, annotated by hand on a PenEcho canvas
Create on the canvas. Bring feedback into the conversation.

Diagrams

Professional diagrams. On canvas.

Architecture, sequences, and workflows — drafted by AI, refined by you.

Architecture

Kubernetes cluster

Sequences

Event notifications

Workflows

Release preparation

Made with PenEcho

Things worth working through.

From a new term to an intuition.

Follow a token through a Transformer, open up one layer, and keep the diagram beside the code.

01 / 05

PenEcho Cloud

Close the laptop.
Not the idea.

Private projects and saved revisions live in Cloud. Pick up on another device, or reach your own PenEcho host through a Linked Device.

Keep your work with Cloud

Echoes

Someone else’s insight.
Your next beginning.

Explore shared canvases and widgets. Bring a community widget into your canvas, or Echo a public Craft while keeping its origin connected.

Let an idea keep growing

Good company. Shared curiosity.

An open canvas. A little support.

PenEcho is an official member of Kimi Open Source Friends and receives API credits from Kimi. Independently made, with your choice of model.

Meet our supporters
MOONSHOT AI // 2026 — KIMI OPEN SOURCE FRIENDS

Questions

PenEcho, in a few answers.

What is PenEcho?

PenEcho is an open-source 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, or in the browser at penecho.ai.

What is PenEchoLLM?

PenEchoLLM is the model behind PenEcho's smart suggestions. When you pause after writing, it ranks the most useful next actions, such as Solve, Typeset, Plot graph or Organize as Note, and decides whether Canvas AI or the PenEcho Agent should carry them out. 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.

What are PenEcho Notes & Cards?

Notes & Cards turn any part of your canvas into a reusable card. Circle content and PenEcho creates a knowledge card for concepts, formulas, worked examples and references, or a work note for ideas, work, meetings and to-dos, keeping your original handwriting. Cards are categorized automatically and collected in the Library, where you can search, bookmark, review and add them to other canvases.

Which AI models and agents work with PenEcho?

Sign in to use PenEcho models, bring your own OpenAI- or Anthropic-compatible API key, or reuse a signed-in Codex, Claude Code or Kimi CLI. Agents such as Codex, Claude Code, Kimi and Cursor can also draw on the canvas through the PenEcho MCP server.

How do I connect Claude Code or Codex to PenEcho?

Copy the setup prompt from the PenEcho MCP section above and paste it into Claude Code, Codex, Cursor or another MCP agent. Your agent installs the PenEcho plugin and connects https://penecho.ai/mcp; if it asks for authorization, choose Continue as guest. No account is needed. Then ask it to draw something on the canvas, and the canvas opens beside your chat. The desktop app can also connect agents to local canvases from Settings → MCP service.

Is PenEcho free and open source?

Yes. The PenEcho Canvas is open source under AGPL-3.0 and free to download for macOS and Windows or to install with npm. Hosted PenEcho models use account credits; with your own API key or CLI, usage is billed by your provider.

AI that shows,
not just tells.

Start nowDownload PenEcho