fastbrowser

Description

Real-browser automation (JS/SPA pages, screenshots, downloads) and OS accessibility (read/act on web pages and native desktop apps) via the fastbrowser CLI, driven with run_shell.

Parameters

None — this is a document skill; read it, then run the commands below with run_shell.

Discover the CLI commands and the full underlying tool list (100+) via run_shell:

• python3 -m fastbrowser --help — all CLI commands
• python3 -m fastbrowser <command> --help — options for one command
• python3 -m fastbrowser tools --mode names — all tool names
• python3 -m fastbrowser tools --mode compact — name + short description + param names
• python3 -m fastbrowser tools --mode help --name <tool> — one tool's full schema

Example

Run every command below with the run_shell tool, e.g. run_shell("python3 -m fastbrowser fetch https://example.com", timeout=120). Give it a generous timeout — the browser cold start can take a few seconds.

Render a JS page to text (one-shot)

python3 -m fastbrowser fetch "https://example.com" --max-chars 4000

Multi-step in one shot

--steps is a JSON array of {"tool": <name>, "args": {...}}:

python3 -m fastbrowser run --url "https://example.com/login" --steps '[
  {"tool":"type","args":{"selector":"#user","text":"admin"}},
  {"tool":"click","args":{"selector":"button[type=submit]"}},
  {"tool":"extract_text","args":{"max_chars":2000}}
]'

Interactive session (auto daemon; state persists across calls)

python3 -m fastbrowser open "https://example.com"
python3 -m fastbrowser call get_page_title
python3 -m fastbrowser call extract_text --args '{"max_chars":1000}'
python3 -m fastbrowser daemon stop

Screenshots, downloads, JS

python3 -m fastbrowser screenshot /tmp/page.png
python3 -m fastbrowser download "https://host/img.jpg" /tmp/img.jpg --referer "https://host/page"
python3 -m fastbrowser call execute_js --args '{"script":"document.title"}'
python3 -m fastbrowser call execute_js --args '{"function":"async () => { return 42; }"}'

Discover and call any tool (100+)

python3 -m fastbrowser tools --mode compact
python3 -m fastbrowser tools --mode help --name navigate
python3 -m fastbrowser call <tool> --args '<json>'

Accessibility (web + native desktop)

python3 -m fastbrowser ax list
python3 -m fastbrowser ax snapshot
python3 -m fastbrowser ax snapshot --target "desktop:1234"
python3 -m fastbrowser ax act --action click --ref "web:1:ax:42"
python3 -m fastbrowser ax act --action type --ref "desktop:1234:0.1" --text "hello"
python3 -m fastbrowser ax act --action press_key --key "Tab"

ax list shows surfaces (web:<tab>, desktop:<pid>); ax snapshot returns a UiNode tree plus a readable text field. Web refs look like web:<tab>:ax:<id>; native desktop refs like desktop:<pid>:<path>. Desktop accessibility needs no Chromium, but on macOS requires the "Accessibility" permission.

Prerequisites

Check the package is installed in the interpreter fastclaw uses; install if missing:

python3 -c "import fastbrowser; print(fastbrowser.__version__)" || python3 -m pip install fastbrowser

Chromium/Chrome is auto-discovered (or set CHROME_PATH, or attach an existing browser with --cdp-url).

Notes

• Output is JSON on stdout — parse it directly.
• Give run_shell a generous timeout (browser cold start takes a few seconds): run_shell("python3 -m fastbrowser open ...", timeout=120).
• If a result has blocked: true (WAF/anti-bot) or empty content, try the site's mobile/API endpoint or fetch/curl.
• Run daemon stop when finished; the daemon also exits after being idle.