Claude gets a browser locked inside a WASM sandbox

What it does

Dev Browser is a CLI tool that exposes the full Playwright API to AI agents and developers through scripts running in a QuickJS WASM sandbox. It can launch a fresh headless Chromium or attach to an existing Chrome instance, keeping page state alive across multiple script executions. File access is restricted to a temporary directory, so the host filesystem remains off-limits.

The interesting bit

The sandboxing is the real sell: instead of handing an agent an unsupervised Node.js environment, scripts run inside QuickJS WASM with no host access, which makes pre-approving the tool in Claude Code less nerve-wracking. It also includes snapshotForAI, a Playwright helper that returns page state formatted specifically for LLM consumption.

Key highlights

• Sandboxed execution via QuickJS WASM; scripts get no host filesystem or network access
• Persistent named pages survive across separate script invocations
• Attaches to existing Chrome via remote debugging or launches its own Chromium
• Exposes the full Playwright Page API, including clicks, locators, evaluate, and screenshots
• Claims lower time and cost than Playwright MCP and the Claude Chrome Extension in the project’s own benchmarks (3m 53s / $0.88 vs. 4m 31s / $1.45 and up)

Caveats

• Claude Code integration requires pre-approval in settings before the tool can run without permission prompts
• The Windows build depends on a native executable rather than a pure Node.js shim
• A legacy plugin installation path is still documented, suggesting the integration method is evolving

Verdict

Worth a look if you want an AI agent to scrape, test, or interact with the web without handing it the keys to your machine. Skip it if you already have a trusted Playwright setup and do not need the sandboxing or agent-specific snapshot formatting.