Agent Browser

Browser Automation with agent-browser

The CLI uses Chrome/Chromium via CDP directly. Install via npm i -g agent-browser, brew install agent-browser, or cargo install agent-browser. Run agent-browser install to download Chrome. Existing Chrome, Brave, Playwright, and Puppeteer installations are detected automatically. Run agent-browser upgrade to update to the latest version.

Core Workflow

Every browser automation follows this pattern:

1. Navigate: agent-browser open
2. Snapshot: agent-browser snapshot -i (get element refs like @e1, @e2)
3. Interact: Use refs to click, fill, select
4. Re-snapshot: After navigation or DOM changes, get fresh refs

agent-browser open https://example.com/form
agent-browser snapshot -i
# Output: @e1 [input type="email"], @e2 [input type="password"], @e3 [button] "Submit"

agent-browser fill @e1 "user@example.com"
agent-browser fill @e2 "password123"
agent-browser click @e3
agent-browser wait 2000
agent-browser snapshot -i  # Check result

Command Chaining

Commands can be chained with && in a single shell invocation. The browser persists between commands via a background daemon, so chaining is safe and more efficient than separate calls.

# Chain open + snapshot in one call (open already waits for page load)
agent-browser open https://example.com && agent-browser snapshot -i

# Chain multiple interactions
agent-browser fill @e1 "user@example.com" && agent-browser fill @e2 "password123" && agent-browser click @e3

# Navigate and capture
agent-browser open https://example.com && agent-browser screenshot

When to chain: Use && when you don't need to read the output of an intermediate command before proceeding (e.g., open + wait + screenshot). Run commands separately when you need to parse the output first (e.g., snapshot to discover refs, then interact using those refs).

Handling Authentication

When automating a site that requires login, choose the approach that fits:

Option 1: Import auth from the user's browser (fastest for one-off tasks)

# Connect to the user's running Chrome (they're already logged in)
agent-browser --auto-connect state save ./auth.json
# Use that auth state
agent-browser --state ./auth.json open https://app.example.com/dashboard

State files contain session tokens in plaintext -- add to .gitignore and delete when no longer needed. Set AGENT_BROWSER_ENCRYPTION_KEY for encryption at rest.

Option 2: Chrome profile reuse (zero setup)

# List available Chrome profiles
agent-browser profiles

# Reuse the user's existing Chrome login state
agent-browser --profile Default open https://gmail.com

Option 3: Persistent profile (for recurring tasks)

# First run: login manually or via automation
agent-browser --profile ~/.myapp open https://app.example.com/login
# ... fill credentials, submit ...

# All future runs: already authenticated
agent-browser --profile ~/.myapp open https://app.example.com/dashboard

Option 4: Session name (auto-save/restore cookies + localStorage)

agent-browser --session-name myapp open https://app.example.com/login
# ... login flow ...
agent-browser close  # State auto-saved

# Next time: state auto-restored
agent-browser --session-name myapp open https://app.example.com/dashboard

Option 5: Auth vault (credentials stored encrypted, login by name)

echo "$PASSWORD" | agent-browser auth save myapp --url https://app.example.com/login --username user --password-stdin
agent-browser auth login myapp

auth login navigates with load and then waits for login form selectors to appear before filling/clicking, which is more reliable on delayed SPA login screens.

Option 6: State file (manual save/load)

# After logging in:
agent-browser state save ./auth.json
# In a future session:
agent-browser state load ./auth.json
agent-browser open https://app.example.com/dashboard

See [references/authentication.md](references/authentication.md) for OAuth, 2FA, cookie-based auth, and token refresh patterns.

Essential Commands

# Batch: ALWAYS use batch for 2+ sequential commands. Commands run in order.
agent-browser batch "open https://example.com" "snapshot -i"
agent-browser batch "open https://example.com" "screenshot"
agent-browser batch "click @e1" "wait 1000" "screenshot"

# Navigation
agent-browser open               # Navigate (aliases: goto, navigate)
agent-browser close                   # Close browser
agent-browser close --all             # Close all active sessions

# Snapshot
agent-browser snapshot -i             # Interactive elements with refs (recommended)
agent-browser snapshot -i --urls      # Include href URLs for links
agent-browser snapshot -s "#selector" # Scope to CSS selector

# Interaction (use @refs from snapshot)
agent-browser click @e1               # Click element
agent-browser click @e1 --new-tab     # Click and open in new tab
agent-browser fill @e2 "text"         # Clear and type text
agent-browser type @e2 "text"         # Type without clearing
agent-browser select @e1 "option"     # Select dropdown option
agent-browser check @e1               # Check checkbox
agent-browser press Enter             # Press key
agent-browser keyboard type "text"    # Type at current focus (no selector)
agent-browser keyboard inserttext "text"  # Insert without key events
agent-browser scroll down 500         # Scroll page
agent-browser scroll down 500 --selector "div.content"  # Scroll within a specific container

# Get information
agent-browser get text @e1            # Get element text
agent-browser get url                 # Get current URL
agent-browser get title               # Get page title
agent-browser get cdp-url             # Get CDP WebSocket URL

# Wait
agent-browser wait @e1                # Wait for element
agent-browser wait 2000               # Wait milliseconds
agent-browser wait --url "**/page"    # Wait for URL pattern
agent-browser wait --text "Welcome"   # Wait for text to appear (substring match)
agent-browser wait --load networkidle # Wait for network idle (caution: see Pitfalls)
agent-browser wait --fn "!document.body.innerText.includes('Loading...')"  # Wait for text to disappear
agent-browser wait "#spinner" --state hidden  # Wait for element to disappear

# Downloads
agent-browser download @e1 ./file.pdf          # Click element to trigger download
agent-browser wait --download ./output.zip     # Wait for any download to complete
agent-browser --download-path ./downloads open   # Set default download directory

# Tab management
agent-browser tab list                         # List all open tabs
agent-browser tab new                          # Open a blank new tab
agent-browser tab new https://example.com      # Open URL in a new tab
agent-browser tab 2                            # Switch to tab by index (0-based)
agent-browser tab close                        # Close the current tab
agent-browser tab close 2                      # Close tab by index

# Network
agent-browser network requests                 # Inspect tracked requests
agent-browser network requests --type xhr,fetch  # Filter by resource type
agent-browser network requests --method POST   # Filter by HTTP method
agent-browser network requests --status 2xx    # Filter by status (200, 2xx, 400-499)
agent-browser network request       # View full request/response detail
agent-browser network route "**/api/*" --abort  # Block matching requests
agent-browser network har start                # Start HAR recording
agent-browser network har stop ./capture.har   # Stop and save HAR file

# Viewport & Device Emulation
agent-browser set viewport 1920 1080          # Set viewport size (default: 1280x720)
agent-browser set viewport 1920 1080 2        # 2x retina (same CSS size, higher res screenshots)
agent-browser set device "iPhone 14"          # Emulate device (viewport + user agent)

# Capture
agent-browser screenshot              # Screenshot to temp dir
agent-browser screenshot --full       # Full page screenshot
agent-browser screenshot --annotate   # Annotated screenshot with numbered element labels
agent-browser screenshot --screenshot-dir ./shots  # Save to custom directory
agent-browser screenshot --screenshot-format jpeg --screenshot-quality 80
agent-browser pdf output.pdf          # Save as PDF

# Live preview / streaming
agent-browser stream enable           # Start runtime WebSocket streaming on an auto-selected port
agent-browser stream enable --port 9223  # Bind a specific localhost port
agent-browser stream status           # Inspect enabled state, port, connection, and screencasting
agent-browser stream disable          # Stop runtime streaming and remove the .stream metadata file

# Clipboard
agent-browser clipboard read                      # Read text from clipboard
agent-browser clipboard write "Hello, World!"     # Write text to clipboard
agent-browser clipboard copy                      # Copy current selection
agent-browser clipboard paste                     # Paste from clipboard

# Dialogs (alert, confirm, prompt, beforeunload)
# By default, alert and beforeunload dialogs are auto-accepted so they never block the agent.
# confirm and prompt dialogs still require explicit handling.
# Use --no-auto-dialog (or AGENT_BROWSER_NO_AUTO_DIALOG=1) to disable automatic handling.
agent-browser dialog accept              # Accept dialog
agent-browser dialog accept "my input"   # Accept prompt dialog with text
agent-browser dialog dismiss             # Dismiss/cancel dialog
agent-browser dialog status              # Check if a dialog is currently open

# Diff (compare page states)
agent-browser diff snapshot                          # Compare current vs last snapshot
agent-browser diff snapshot --baseline before.txt    # Compare current vs saved file
agent-browser diff screenshot --baseline before.png  # Visual pixel diff
agent-browser diff url                   # Compare two pages
agent-browser diff url   --wait-until networkidle  # Custom wait strategy
agent-browser diff url   --selector "#main"  # Scope to element

# Chat (AI natural language control)
agent-browser chat "open google.com and search for cats"  # Single-shot instruction
agent-browser chat                                        # Interactive REPL mode
agent-browser -q chat "summarize this page"               # Quiet (text only, no tool calls)
agent-browser -v chat "fill in the login form"            # Verbose (show command output)
agent-browser --model openai/gpt-4o chat "take a screenshot"  # Override model

Streaming

Every session automatically starts a WebSocket stream server on an OS-assigned port. Use agent-browser stream status to see the bound port and connection state. Use stream disable to tear it down, and stream enable --port to re-enable on a specific port.

Batch Execution

ALWAYS use batch when running 2+ commands in sequence. Batch executes commands in order, so dependent commands (like navigate then screenshot) work correctly. Each quoted argument is a separate command.

# Navigate and take a snapshot
agent-browser batch "open https://example.com" "snapshot -i"

# Navigate, snapshot, and screenshot in one call
agent-browser batch "open https://example.com" "snapshot -i" "screenshot"

# Click, wait, then screenshot
agent-browser batch "click @e1" "wait 1000" "screenshot"

# With --bail to stop on first error
agent-browser batch --bail "open https://example.com" "click @e1" "screenshot"

Only use a single command (not batch) when you need to read the output before deciding the next command. For example, you must run snapshot -i as a single command when you need to read the refs to decide what to click. After reading the snapshot, batch the remaining steps.

Stdin mode is also supported for programmatic use:

echo '[["open","https://example.com"],["screenshot"]]' | agent-browser batch --json
agent-browser batch --bail "` where UDID is from `xcrun xctrace list devices`.

## Security

All security features are opt-in. By default, agent-browser imposes no restrictions on navigation, actions, or output.

### Content Boundaries (Recommended for AI Agents)

Enable `--content-boundaries` to wrap page-sourced output in markers that help LLMs distinguish tool output from untrusted page content:

```bash
export AGENT_BROWSER_CONTENT_BOUNDARIES=1
agent-browser snapshot
# Output:
# --- AGENT_BROWSER_PAGE_CONTENT nonce= origin=https://example.com ---
# [accessibility tree]
# --- END_AGENT_BROWSER_PAGE_CONTENT nonce= ---

Domain Allowlist

Restrict navigation to trusted domains. Wildcards like *.example.com also match the bare domain example.com. Sub-resource requests, WebSocket, and EventSource connections to non-allowed domains are also blocked. Include CDN domains your target pages depend on:

export AGENT_BROWSER_ALLOWED_DOMAINS="example.com,*.example.com"
agent-browser open https://example.com        # OK
agent-browser open https://malicious.com       # Blocked

Action Policy

Use a policy file to gate destructive actions:

export AGENT_BROWSER_ACTION_POLICY=./policy.json

Example policy.json:

{ "default": "deny", "allow": ["navigate", "snapshot", "click", "scroll", "wait", "get"] }

Auth vault operations (auth login, etc.) bypass action policy but domain allowlist still applies.

Output Limits

Prevent context flooding from large pages:

export AGENT_BROWSER_MAX_OUTPUT=50000

Diffing (Verifying Changes)

Use diff snapshot after performing an action to verify it had the intended effect. This compares the current accessibility tree against the last snapshot taken in the session.

# Typical workflow: snapshot -> action -> diff
agent-browser snapshot -i          # Take baseline snapshot
agent-browser click @e2            # Perform action
agent-browser diff snapshot        # See what changed (auto-compares to last snapshot)

For visual regression testing or monitoring:

# Save a baseline screenshot, then compare later
agent-browser screenshot baseline.png
# ... time passes or changes are made ...
agent-browser diff screenshot --baseline baseline.png

# Compare staging vs production
agent-browser diff url https://staging.example.com https://prod.example.com --screenshot

diff snapshot output uses + for additions and - for removals, similar to git diff. diff screenshot produces a diff image with changed pixels highlighted in red, plus a mismatch percentage.

Timeouts and Slow Pages

The default timeout is 25 seconds. This can be overridden with the AGENT_BROWSER_DEFAULT_TIMEOUT environment variable (value in milliseconds).

Important: open already waits for the page load event before returning. In most cases, no additional wait is needed before taking a snapshot or screenshot. Only add an explicit wait when content loads asynchronously after the initial page load.

# Wait for a specific element to appear (preferred for dynamic content)
agent-browser wait "#content"
agent-browser wait @e1

# Wait a fixed duration (good default for slow SPAs)
agent-browser wait 2000

# Wait for a specific URL pattern (useful after redirects)
agent-browser wait --url "**/dashboard"

# Wait for text to appear on the page
agent-browser wait --text "Results loaded"

# Wait for a JavaScript condition
agent-browser wait --fn "document.querySelectorAll('.item').length > 0"

Avoid wait --load networkidle unless you are certain the site has no persistent network activity. Ad-heavy sites, sites with analytics/tracking, and sites with websockets will cause networkidle to hang indefinitely. Prefer wait 2000 or wait instead.

JavaScript Dialogs (alert / confirm / prompt)

When a page opens a JavaScript dialog (alert(), confirm(), or prompt()), it blocks all other browser commands (snapshot, screenshot, click, etc.) u

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Source & license

This open-source skill is cataloged on AgentStack and links to its original source — we do not rehost the code.

• Author: alexdcd
• Source: alexdcd/Mafia-Claude-Skills
• License: Apache-2.0
• Homepage: https://mafiaia.com/

Install and usage instructions live in the source repository linked above.