Browser Tools

Browser automation, debugging, and anti-detect browsing CLI. Provides:

• Raw CDP passthrough - Any Domain.method goes straight to the running browser, with protocol help read live from it
• Snapshot-based page automation - Accessibility-tree snapshots and UID interaction (snapshot, click --uid, fill --uid), in Python over CDP
• Curated verbs for the common path - eval, press, hover, type, wait-text and network-get beside those three: the interactions whose raw CDP form is JavaScript or prose quoted inside JSON inside a shell line
• One answer for every dialog - --dialog fixes the reply to every JavaScript dialog before the invocation starts, and every dialog it answered is reported back under dialogs
• Named browser instances - Long-lived Chrome with a registry and named profiles that keep a login across restarts
• External browsers - --endpoint and --chrome-profile drive a Chrome you started for debugging on a data directory of its own, writing nothing to the registry
• Frame-aware tools - Iframe/CDP frame tree management, execution context resolution, and storage inspection
• Interstitial detection - Multi-signal heuristic detection for Cloudflare, DataDome, Akamai, PerimeterX, Imperva, AWS WAF, and other challenge pages
• Camoufox anti-detect browsing - Fingerprint-injected Firefox-based browsing for bot-protected sites
• Anything else CDP can do - File upload, viewport emulation, cookies, PDF export and page management have no curated verb and need none; bt guide has a worked example of each
• Performance captures - trace writes Chrome trace JSON and can drive the interaction it is capturing; heap writes a .heapsnapshot; insights reads a trace back as English, behind the optional runtime below
• CPU profiling - browser-tools-profiler, a second command installed alongside bt, with timed capture and threshold-triggered capture

Quick Start

Installation

# Using uv (recommended)
uv tool install browser-tools

# Or with pip
pip install browser-tools

Usage

# Run the CLI (`bt` is an alias for `browser-tools`)
bt --help

# Launch a browser. It is registered by name and outlives this command, so
# later verbs drive the same Chrome and share its page and login state.
bt launch

# Navigate through the raw CDP passthrough, then read the page.
bt Page.navigate '{"url": "https://example.com"}'
bt snapshot

# Interact by UID from that snapshot.
bt click --uid 1-13

# When the page is blocking, ask directly.
bt detect

bt status          # registered instances and their page targets
bt stop            # close the browser and retire its registry entry

Omit INSTANCE while exactly one instance is running; with several, every verb names the candidates rather than guessing. bt help Domain.method reads the protocol schema from the running browser.

bt launch derives an instance name from the current directory and prints the chosen name in its JSON result. Repeated unnamed launches from one directory succeed with the first free two-digit suffix, such as browser-tools-01, browser-tools-02, then browser-tools-03. There is no caller-chosen name, so use the printed value as the handle for later commands.

bt guide is the manual. It is the complete CLI surface -- every verb, every refusal with its exit code, the login walkthrough, the UID rule, the performance captures and the --endpoint rules -- and reading it is enough to drive a browser with this tool. A test fails the build when a verb has no entry in it.

To drive a Chrome you started yourself, pass its endpoint or its data directory instead of an instance name. It has to be a Chrome started for debugging on a directory of its own. The browser you already have open will not do: measured on Chrome 153, it refuses remote debugging on its default data directory, writes no port file, and starts no endpoint.

DevTools remote debugging requires a non-default data directory. Specify this
using --user-data-dir.

So start one:

"/Applications/Google Chrome.app/Contents/MacOS/Google Chrome" \
  --user-data-dir="$HOME/.local/share/bt-debug-profile" \
  --remote-debugging-port=0

--remote-debugging-port=0 asks Chrome for a free port and records it in that directory's DevToolsActivePort file. Log in by hand in that window, then reach it by the directory or by the endpoint:

bt snapshot --chrome-profile ~/.local/share/bt-debug-profile
bt click --uid 0BDAEF756714-14 --chrome-profile ~/.local/share/bt-debug-profile
bt snapshot --endpoint http://127.0.0.1:PORT
bt snapshot --endpoint ws://127.0.0.1:PORT/devtools/browser/ID

Nothing is written to the registry, so status does not list it and stop and cleanup cannot reach it -- which is what keeps them away from your own Chrome profile directory. Only 127.0.0.1 and ::1 are accepted; forward a remote browser with ssh -L 9787:127.0.0.1:9787 <host>. Do not use 9222 for any of this: it is the DevTools default port, so on a machine someone is working on, whatever answers there is most likely their own browser. Browser.close and Browser.crash are refused over --endpoint.

Measured on this machine's Chrome 153 with the person at the keyboard: a Chrome started on its own data directory with --remote-debugging-port needs no Allow click and shows no automation banner, so no person needs to be present for the working shape. The per-connection Allow flow belongs to the chrome://inspect remote-debugging toggle, which Chrome 153 refuses on the default data directory - the everyday browser cannot be attached to at all. The manual's EXTERNAL BROWSERS section carries the refusals, the timeouts, and what a timeout does and does not prove.

Development setup

# Clone and install in editable mode
git clone https://github.com/dungle-scrubs/browser-tools.git
cd browser-tools
uv sync

Runtime requirements:

• Chrome Canary by default (the default channel is canary). Use another installed channel with --channel stable|beta|dev, e.g. --channel stable for regular Google Chrome.
• Camoufox (camoufox fetch) for anti-detect Firefox workflows, with the camoufox extra

The default install depends on websockets only, and pip install browser-tools brings no Node.js with it.

One opt-in adds a Node runtime, and nothing else does. bt insights --setup installs the pinned trace engine from a committed lockfile into the installed package, so bt insights can read a trace back as English. It needs Node.js 22+ and npm on PATH, runs only npm ci --omit=dev --ignore-scripts, and is never run for you. Skip it and the rest of the tool is unaffected; bt insights is then exit 2 and names the command.

Architecture

Five layers. Each upper layer consumes only the layer below it, and every curated tool calls the same CDP send path the raw passthrough uses -- so any method the installed browser supports works through bt Domain.method whether or not a verb exists for it.

cli.py                       CLI entry point (argparse, verb dispatch, exit codes)
        |
        +-- lifecycle.py             launch / status / stop / cleanup over the registry
        |       +-- camoufox_runner.py   Camoufox host process (`launch --engine camoufox`)
        |       +-- process_utils.py     Chrome process and port utilities
        |
        +-- endpoint.py              `--endpoint URL`: loopback check, refusals
        |       +-- chrome_discovery.py  `--chrome-profile DIR`: read DevToolsActivePort
        |       +-- external_connection.py Bounded external connections, approval handshake
        |       +-- devtools_http.py     DevTools HTTP reads, to the validated address only
        |
        +-- passthrough.py           Raw `Domain.method` send + the focus guard
        +-- curated.py               The curated verbs over one short-lived CDP handler
        |       +-- curated_runtime.py   eval / press / hover / type / wait-text / network-get
        |       +-- dialog_policy.py     The invocation's fixed answer to every dialog
        |
        +-- captures.py              Bounded captures: `trace` and `heap`
        +-- insights.py              `insights --setup` and offline trace analysis
        +-- extras.py                Optional-dependency gating
        +-- step_run.py              A Step Run: one invocation, one session, many steps
        |       +-- step_list.py         Read a Step List; refuse a bad one before step 1
        |
        +-- one_shot.py              Connect, resolve a page target, attach, detach
        |       +-- attached_session.py  The handler's client over an attached session
        |
        +-- events.py                attach / wait / console-list / network-list
        +-- list_verbs.py            frames / storage
        +-- usage.py                 The one exception that means exit 2
        +-- user_settings.py         The persistent settings file (window border)
        |
        +-- core/                    Vendored chrome-agent core (RFC-01; see NOTICE)
        |       +-- registry.py          Named instances, liveness, retirement
        |       +-- launcher.py          Chrome launch (windowless, background first window)
        |       +-- supervisor.py        Per-instance window marking and retirement
        |       +-- cdp_client.py        CDP WebSocket client and target discovery
        |       +-- attach.py            Isolated event subscriptions
        |       +-- protocol.py          Live protocol schema for `help`
        |       +-- fingerprint.py       Launch-flag fingerprint profiles
        |
        +-- cdp_handler.py           CDP tool implementations (snapshot, click, fill, ...)
        |       +-- native_snapshot.py   Accessibility-tree snapshot and UID scheme
        |       +-- native_interaction.py UID click / fill
        |       +-- frame_manager.py     Frame tree management
        |       +-- frame_sessions.py    One session per out-of-process frame
        |       +-- interstitial.py      Challenge detection and the retry policy
        |       +-- screencast.py        Screencast capture state machine
        |       +-- screenshot_utils.py  Blank-frame detection
        |       +-- tool_registry.py     Single source of truth for CDP tool routing
        |       +-- mcp_response.py      Response envelope builders
        |
        +-- profiler.py              Standalone CPU profiler (`browser-tools-profiler`)

The CLI is the only surface. The optional MCP front and the persistent-session stack behind it were deleted in RFC-01 Phase 5; there is no daemon, no broker, and no listening socket.

Keeping login state across calls

Login state lives in a browser profile directory and survives only while the same directory is reused. To keep a session logged in:

• Use a named profile: bt launch --profile <name>. Named profiles persist across restarts and are unaffected by headed/headless switches, viewport, or which directory you invoke from.
• A profile is held by at most one live instance. Launching into a profile another instance holds fails naming the holder rather than opening a second browser on the same profile directory. This is profile exclusivity, not a limit on launches from one working directory: repeated unnamed launches from one working directory succeed with numbered instance-name suffixes.
• Without --profile, a launch gets a fresh ephemeral directory and starts logged out.
• bt profile list shows every profile with its path and its live holder, and bt profile delete NAME removes one. Deleting a profile deletes its login state; cleanup never removes a profile on age.

Profiles live in durable storage: $BROWSER_TOOLS_PROFILES_DIR, else $XDG_DATA_HOME/browser-tools/profiles, else ~/.local/share/browser-tools/profiles. They used to live under /tmp, where the operating system deleted every signed-in session at boot, silently. A profile still there is listed with "legacy": true; bt profile migrate moves them all across (--dry-run first, --back to reverse it), and launch --profile NAME brings that one forward by itself.

• Camoufox persists login state only when you pass --profile; without it, every launch starts logged out.

Development

uv sync
uv run ruff check src/ tests/
uv run pytest

License

MIT - see LICENSE.

Contributing

See CONTRIBUTING.md for development setup and guidelines. All contributors are expected to follow the Code of Conduct.

Security

Found a vulnerability? See SECURITY.md for responsible disclosure.