A browser-based MicroPython IDE. Plug in a microcontroller, open the page, write code — no installs, no drivers, no extensions.

Features

Python editor with syntax highlighting (CodeMirror 6).
Live REPL over the Web Serial API at 115200 baud, with raw-paste mode for fast uploads of larger programs.
Run on device — execute the editor's contents on the connected board and watch output stream into the integrated terminal.
Local file access — open .py files from your computer via the File System Access API; the last folder you opened is restored on reload.
Device filesystem browser — list, read, write, and delete files on the microcontroller; create directories.
AI coding assistant (optional) — a built-in chat panel that can read and write the editor, run snippets, and inspect the device filesystem. Powered by Google Gemini; bring your own API key.
Progressive Web App — installable on desktop and mobile.
Light / dark themes, toggled from the toolbar.

Requirements

A Chromium-based browser (Chrome, Edge, Brave, Opera, Arc). The Web Serial and File System Access APIs aren't available in Firefox or Safari.
A microcontroller running MicroPython. Raspberry Pi Pico is the primary target, but any MicroPython device that exposes a USB serial REPL should work.

Running locally

git clone https://github.com/andreban/cobweb
cd cobweb
npm install
npm run dev          # http://localhost:5173

Production build:

npm run build        # output in dist/
npm run preview      # preview the production build

Using the AI assistant

The AI panel is opt-in. To enable it:

Open Settings in the toolbar.
Paste a Google AI Studio API key and pick a Gemini model.
Save. The key is stored locally in your browser only — no server is involved.

Development

npm run lint         # ESLint
npm run format       # Prettier (auto-fix in src/)
npm run test         # Vitest (single run)
npm run test:watch   # Vitest (watch mode)

Built with React 19, Vite 8, TailwindCSS 4, CodeMirror 6, and xterm.js. Tests run on happy-dom via Vitest.

Architecture details and contribution conventions live in CLAUDE.md, docs/PRD.md, and docs/SPEC.md. Per-feature design docs live in docs/<feature>/ and are moved to docs/archive/<feature>/ once shipped.

License

Apache-2.0.