What it does

Bolt.new is an open-source AI web development agent. You prompt it in natural language, and it scaffolds, edits, runs, and deploys full-stack JavaScript applications entirely inside your browser. No local Node.js install, no Docker, no terminal juggling. The hosted version is free with daily token limits; paid plans add more tokens and private projects.

The interesting bit

The trick isn’t the LLM—it’s the sandbox. Bolt.new runs on StackBlitz’s WebContainers, which spin up actual Node.js environments inside the browser via WebAssembly. The AI gets filesystem access, a package manager, a terminal, and the browser console. That means it can npm install, hit runtime errors, read the stack trace, and fix its own mistakes without you copy-pasting anything.

Key highlights

• Supports Vite, Next.js, Astro, and anything else that runs on StackBlitz
• Deploy to production directly from chat
• “Enhance prompt” button lets the LLM rewrite your prompt before execution
• Batching simple instructions (e.g., “change theme, add mobile CSS, restart dev server”) saves API tokens
• The codebase is open source if you want to build your own WebContainers-powered agent

Caveats

• Explicitly in beta; expect rough edges
• Free tier pauses AI interactions once daily tokens are exhausted
• README is vague on exact token limits and pricing tiers

Verdict

Worth a spin if you want to prototype full-stack JS apps without touching localhost. Skip it if you need non-JavaScript stacks or fine-grained control over your deployment pipeline.