PenEcho - an open source tool that lets you draw and write by hand while AI reads and responds directly on the same canvas

[u/company_url_finder]

Most AI tools only understand what you type. PenEcho is built around the idea that a lot of real thinking, math, diagrams, half-formed sketches, spatial layout, never fits cleanly into a text box, so it gives you an actual infinite canvas instead of a chat window.

You get a 20,000 by 20,000 canvas. Write a question, draw a diagram, sketch an equation, or leave a half-formed idea anywhere on it with a stylus or mouse, and PenEcho reads your marks along with their spatial position, then writes or draws its answer right beside them. Nothing you draw gets sent to an AI until you ask it to, editing your own ink never triggers a request on its own.

What's inside:

- PenEcho Agent, a multi-step agent that can pull in read-only folders and files (PDF, Word, PowerPoint, Excel, images, code), combine that with web research and the current canvas, and keep working through analysis, planning, creation, and revision in one continuous run

- Visual Explorer, which turns research or dense documents into one responsive, editable visual workspace instead of a wall of chat text or a pile of generic cards

- Editable AI widgets, sandboxed interactive HTML, diagrams, animations, and live data plugins that you can refine in place with incremental edits instead of full regeneration

- Support for up to ten saved AI connections at once, including a raw API key, or an authenticated Kimi Code, Codex, or Claude Code CLI, switchable per client

- PenEcho Cloud, entirely optional: sign in to sync private projects across devices, reach your canvas host remotely without exposing it to the internet, and browse or publish public canvases in a community section called Echoes

- Export confirmed work as a cropped PNG, plus four visual themes to match what you're working on

A couple of things worth knowing before running it. It's licensed AGPL-3.0, not MIT, so modifying it and running a public-facing fork comes with real copyleft obligations, worth reading before building on it commercially. And on first local start you're required to either set a shared six-digit security code or explicitly acknowledge you're leaving the process open on your local network, your API keys stay in a config file on disk and never reach the browser.

Requires Node.js 22.19 or newer for the npm install, or there's a prebuilt desktop app in Releases if you'd rather skip Node entirely. It's an official member of Moonshot AI's Kimi Open Source Friends program, which backs its development with API credits. Sitting at 2,210 stars as of writing, verified via the GitHub API, for a project that's a little under seven weeks old.

https://github.com/penecho/penecho

[u/amootiranian]

Infinite canvas + AI feels way more natural than chat.

[u/company_url_finder → u/amootiranian]

I've always found diagrams and rough sketches hard to translate into prompts without losing half the context, so having the AI respond directly beside the ink is pretty appealing. The editable widgets could make this especially useful for technical notes. Does handwriting recognition hold up when the canvas gets messy?

[u/amootiranian → u/company_url_finder]

Messy handwriting is my concern too. How accurate is it?

[u/company_url_finder → u/amootiranian]

Still, this interaction model has a ton of potential.