NanoCodana: open-source Claude Code-style coding agent that runs entirely in the browser
andrepimentaa7 · reddit · 2026-09-03
A developer rebuilt Claude Code's agent loop, system prompt, and tool-based workflow as NanoCodana, a standalone runtime that lives entirely inside a browser tab (MIT, on npm).
How it works: browsers lack Bash, so NanoCodana implements a virtual shell via just-bash running in JavaScript, plus familiar coding-agent tools (Read/Edit/Grep, descriptions inspired by Claude Code) and IndexedDB for persisting the project filesystem. Zero infrastructure: no server, no model proxy, no project database in the middle.
Core and ecosystem: @nanocodana/core contains the agent loop, file tools, virtual shell, tool approvals, MCP support, and Agent Skills. An app can supply its own filesystem/sandbox, pick the model, and build its own UI around the agent. The same core runs in the browser, Node, serverless, edge, or a VM, sandboxed by default. The author built Sharables on it, letting you create real React Native apps (Expo Snack) in the browser for free, connecting to Claude, a local agent, or a free model.
The vision: agents can now live inside the app itself. The author asks what NanoCodana would need before you'd embed it in your own apps.
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