Skip to main content

Documentation Index

Fetch the complete documentation index at: https://mintlify.com/cdpdriver/zendriver/llms.txt

Use this file to discover all available pages before exploring further.

This example demonstrates how to monitor network traffic by listening to Chrome DevTools Protocol (CDP) events. You can intercept HTTP requests and responses to debug, analyze, or modify network behavior.

​
What it does

The script:
  1. Sets up handlers for network request and response events
  2. Navigates to Google and performs a search
  3. Logs all HTTP requests with their headers
  4. Logs all HTTP responses
  5. Downloads all URLs found on the page

​
Complete code

from zendriver import cdp, loop, start


async def main() -> None:
    browser = await start()

    tab = browser.main_tab
    tab.add_handler(cdp.network.RequestWillBeSent, send_handler)
    tab.add_handler(cdp.network.ResponseReceived, receive_handler)

    tab = await browser.get("https://www.google.com/?hl=en")

    reject_btn = await tab.find("reject all", best_match=True)
    await reject_btn.click()

    search_inp = await tab.select("textarea")
    await search_inp.send_keys("undetected zendriver")

    search_btn = await tab.find("google search", True)
    await search_btn.click()

    for _ in range(10):
        await tab.scroll_down(50)

    await tab
    await tab.back()

    search_inp = await tab.select("textarea")

    for letter in "undetected zendriver":
        await search_inp.clear_input()
        await search_inp.send_keys(
            "undetected zendriver".replace(letter, letter.upper())
        )
        await tab.wait(0.1)

    all_urls = await tab.get_all_urls()
    for u in all_urls:
        print("downloading %s" % u)
        await tab.download_file(u)

    await tab.sleep(10)


async def receive_handler(event: cdp.network.ResponseReceived) -> None:
    print(event.response)


async def send_handler(event: cdp.network.RequestWillBeSent) -> None:
    r = event.request
    s = f"{r.method} {r.url}"
    for k, v in r.headers.items():
        s += f"\n\t{k} : {v}"
    print(s)


if __name__ == "__main__":
    loop().run_until_complete(main())

​
Key techniques

​
CDP event handlers

Add handlers to listen for Chrome DevTools Protocol events: 
tab.add_handler(cdp.network.RequestWillBeSent, send_handler)
tab.add_handler(cdp.network.ResponseReceived, receive_handler)

​
Request inspection

Access detailed request information in your handler: 
async def send_handler(event: cdp.network.RequestWillBeSent) -> None:
    r = event.request
    print(f"{r.method} {r.url}")
    for k, v in r.headers.items():
        print(f"\t{k} : {v}")

​
Response inspection

Access response data: 
async def receive_handler(event: cdp.network.ResponseReceived) -> None:
    print(event.response)

​
URL extraction

Get all URLs from the current page: 
all_urls = await tab.get_all_urls()
for u in all_urls:
    await tab.download_file(u)
Use browser navigation controls: 
await tab.back()  # Go back in history

​
Input manipulation

Clear and modify input fields: 
await search_inp.clear_input()
await search_inp.send_keys("new text")

​
Running the example

  1. Save the code to a file (e.g., network_monitor.py)
  2. Run it with Python:
python network_monitor.py
  1. Watch the console output to see all network requests and responses

​
Use cases

  • Debugging: See exactly what requests your automation is making
  • Performance analysis: Identify slow or failing requests
  • API inspection: Discover undocumented API endpoints
  • Security testing: Analyze headers and authentication flows
  • Data extraction: Capture API responses for further processing

​
Available CDP events

You can listen to many other CDP events beyond network monitoring:
  • cdp.network.RequestWillBeSent - Before a request is sent
  • cdp.network.ResponseReceived - When a response is received
  • cdp.network.LoadingFinished - When a resource finishes loading
  • cdp.network.LoadingFailed - When a resource fails to load
  • cdp.page.FrameNavigated - When a frame navigates
  • And many more from the Chrome DevTools Protocol specification

Build docs developers (and LLMs) love

Get started for freeTalk to us