Command-line flags

Flags

Steps go to stderr; the status, cost, step count, why a run stopped short, and the answer go to stdout. --json prints the full result: every step, the quotes behind the answer, and cost by component.

Flag	Effect
--start URL	the first page; worked out from the task when omitted
--context TEXT	background the run may use but never treats as the task
--local	local Chrome instead of a cloud browser
--cloud	force the cloud browser even when FASTBROWSE_PROFILE or FASTBROWSE_HEADED is set
--headed	show the local Chrome window (implies --local)
--profile DIR	keep the local Chrome profile in DIR, so sign-ins persist (implies --local)
--cloud-profile ID	run on a signed-in Browser Use Cloud profile
--fetch	read pages over HTTP with no browser, for a task that only reads
--fetch-first	read over HTTP, and start a browser only if the task needs one
--cdp-url URL, --cdp-port PORT	drive a browser already running, at a ws:// URL or on 127.0.0.1:PORT
--attach	with --cdp-url or --cdp-port, drive a window already open instead of opening a tab
--target-match TEXT	attach to the first window whose title or URL contains TEXT (implies --attach)
--foreground	bring the run's tab to the front instead of working behind the current one
--proxy-country CC	browse from that country (uk, de, ...; default us)
--authorize	allow submit, pay, delete and send; otherwise the run stops at needs_confirmation
--secret NAME=ENV_VAR[@ORIGIN]	let the agent type $ENV_VAR on ORIGIN (https://*.site.com covers its hosts), or on the --start origin; models see NAME only
--bitwarden ITEM	use a vault login on the origin its saved URIs match, including its one-time code
--max-steps N, --max-dollars N	bound steps and model spend; unlimited by default
--downloads DIR	keep downloaded files
--json	print the full result
--trace FILE	append each model call, read and check to FILE as JSON lines (- for stderr); FASTBROWSE_TRACE does the same for serve and MCP
--record FILE	save a captioned MP4 of the run (needs ffmpeg); it shows what the pages showed, so watch it before sharing
--no-cursor	don't draw the agent's cursor. By default it is drawn with Cua Driver over a Chrome window that shows the run (--foreground, or an attached front tab; needs cua-driver, and X11 on Linux), and skipped anywhere else
--cursor	also bring the window to the front, so the cursor is always drawn

export SAUCE_PASSWORD=secret_sauce
fastbrowse "Log in as standard_user with the saved password and add the backpack to the cart." \
  --start https://www.saucedemo.com/ --secret password=SAUCE_PASSWORD --authorize