fastcdp provides an async Python client for the Chrome DevTools
Protocol (CDP)
over WebSocket. It auto-discovers Chrome’s debug port, loads the full
protocol schema from bundled JSON files, and exposes every CDP domain as
a Python attribute with auto-generated signatures and docstrings —
e.g. await cdp.page.navigate(url=...).
It includes a
Page class for
tab-scoped operations, event subscription via
cdp.on()/cdp.wait_event(), navigation helpers (goto,
wait_for_selector, wait_for), screenshot capture, and accessibility
tree access. A
cdp_search
utility lets you search CDP commands by name or description. For use
inside safepyrun sandboxes,
cdp_yolo()
registers all CDP classes.
Install latest from pypi
$ pip install fastcdpfrom fastcdp import *Chrome 146+ has built-in remote debugging support. Navigate to
chrome://inspect/#remote-debugging and enable “Allow remote debugging
for this browser instance”:
Connect to Chrome (which will pop up a permissions window):
cdp = await CDP.connect()Every CDP domain is available as an attribute with auto-generated
signatures. You can search for commands with
cdp_search:
cdp_search('screenshot')"Emulation.setVisibleSize: Resizes the frame/viewport of the page. Note that this does not affect the frame's container\n(e.g. browser window). Can \nHeadlessExperimental.beginFrame: Sends a BeginFrame to the target and returns when the frame was completed. Optionally captures a\nscreenshot from the res\n evt Overlay.screenshotRequested: Fired when user asks to capture screenshot of some area on the page.\nPage.captureScreenshot: Capture page screenshot."
List open pages and attach to one:
ps = await cdp.pages
pg = ps[0]
pg['title']'l:SolveIT - scratch◀️chats'
tid = pg['targetId']
sid = await cdp.attach(tid)
await cdp.eval('document.title', sid)'l:SolveIT - scratch◀️chats'
The Page class
wraps a tab with its own session, so you don’t need to pass sid
everywhere:
page = await cdp.new_page()
await page.goto('https://httpbin.org/forms/post')You can wait_for any js expression to be truthy, and have it returned:
await page.wait_for('document.title')'4. httpbin.org/forms/post'
Take a screenshot of the page:
img = await page.screenshot()Clean up when done:
await page.close()
await cdp.close()See CDP docs
for full details.