Agent browser

agent-browser — fleet default for browser automation

A native-Rust browser-automation CLI designed for AI agents. Compact text output minimises context usage. Use it instead of heavier browser stacks for shell-driven web tasks.

Install

npm install -g agent-browser      # all platforms
# or: brew install agent-browser  # macOS
agent-browser install             # download Chrome (first run only)
# try without installing:
npx agent-browser open example.com

Core loop (ref-based)

agent-browser open example.com
agent-browser snapshot -i          # accessibility tree with refs: heading "..." [ref=e1], link "..." [ref=e2]
agent-browser click @e2            # act on a ref from the snapshot
agent-browser screenshot page.png
agent-browser close

Why refs (the context win)

snapshot returns a compact accessibility tree where each element has a ref (@e1, @e2):

• Context-efficient: ~200-400 tokens vs ~3000-5000 for full DOM.
• Deterministic: a ref points to the exact element from the snapshot (no fragile selectors).
• Fast: no DOM re-query. AI-friendly: text output parses naturally.

What it covers (50+ commands)

Navigation, forms, screenshots, network control, storage/cookies/auth-state, file upload/download, tabs, frames, debugging. Built-in: video recording, streaming, profiler, diffing. First-class docs for React/Web Vitals, init scripts, and Next.js + Vercel. Stateful: sessions, profiles, proxy, security controls — good for long-running agents.

React DevTools introspection (v0.27+)

Launch a browser with React DevTools pre-loaded:

agent-browser open --enable react-devtools http://localhost:3000

React DevTools CLI (v0.27+)

Launch with --enable react-devtools for React component introspection:

Command	Description
react tree	Print React component tree with fiber IDs
react inspect <id>	Inspect props, hooks, state, source for one component
react renders start/stop	Profile re-renders
react suspense --only-dynamic --json	Walk Suspense boundaries, classify static vs dynamic

Core Commands

Command	Description
react tree	Print the React component tree with fiber IDs
react inspect <id>	Inspect props, hooks, state, and source for one component
react renders start	Begin recording component render commits
react renders stop [--json]	Stop recording and print a render profile
react suspense [--only-dynamic] [--json]	Walk Suspense boundaries, classify static vs dynamic

Typical workflow:

# Open with React DevTools
agent-browser open --enable react-devtools http://localhost:3000
# Inspect component tree
agent-browser react tree
# Inspect a specific component
agent-browser react inspect 42
# Profile re-renders after an interaction
agent-browser click @e3
agent-browser react renders stop
# Check Suspense boundaries
agent-browser react suspense --only-dynamic

If the session already has a browser without the hook, pass --enable react-devtools to relaunch with it installed.

Web Vitals

Measure Core Web Vitals on any site:

agent-browser vitals
agent-browser vitals https://example.com --json

Reports LCP, CLS, TTFB, FCP, INP, and hydration timing when available (React profiling build).

SPA navigation

Client-side navigation without full reload:

agent-browser pushstate /dashboard
agent-browser wait --load networkidle
agent-browser snapshot -i

On Next.js apps, uses window.next.router.push so RSC fetches still run. Other frameworks fall back to history.pushState.

Integration with Next.js 16.3

Combined with the next-dev-loop skill (Next.js 16.3+), agent-browser gives agents the full dev feedback loop:

# Install the skill
npx skills add vercel/next.js --skill next-dev-loop
# In your agent prompt: "After every edit, verify the page still works at runtime using the next-dev-loop skill."

Architecture

Client-daemon: a Rust CLI talks to a native Rust daemon that drives Chrome over CDP. The daemon starts automatically and persists between commands.

When to use vs other tools

• Default for shell-driven browser work (cheapest context, deterministic).
• Use Playwright/Stagehand only when you need their specific ecosystem features.
• Cross-platform: macOS (arm64/x64), Linux (arm64/x64), Windows (x64).

Works with: Claude Code, Cursor, Copilot, Codex, Gemini, opencode, and any agent that runs shell commands.