# --cdp-webdriver

Source: https://zshot-cli.com/reference/flags/server/cdp-webdriver/
Markdown: https://zshot-cli.com/reference/flags/server/cdp-webdriver/index.md
Section: [Reference](https://zshot-cli.com/reference/) › [Flags](https://zshot-cli.com/reference/flags/) › [Server](https://zshot-cli.com/reference/flags/server/)
CLI: `--cdp-webdriver` · REST: CLI only
License: [Pro](https://zshot-cli.com/support/licenses/pro)

Serves chromedriver's attach beside the [`--cdp`](/reference/flags/server/cdp) endpoint, so a WebDriver client drives the browser through `goog:chromeOptions.debuggerAddress`. Requires `--cdp`.

| Addition | Value |
| --- | --- |
| `GET /json/version`, `/json/list`, `/json` | Chromium's discovery documents, naming the relay's endpoints |
| `/devtools/page/<id>` | A socket per page |
| `ZSHOT_DEBUGGER_ADDRESS` | `HOST:PORT` for the debugger address, set for a `--cdp -- COMMAND` |

Use a chromedriver of the same major version as ZShot's Chromium, which `/json/version` reports as `Browser`; another version refuses the session.

## Warning: Window Resizing Is Poorly Supported

ZShot answers WebDriver's window calls itself, since its browser has no window. Setting the window resizes the page's layout, but a screenshot keeps the browser's starting size, and the window and screen the page reads stay at their first values.

## Warning: The Attach Carries No Token

Any local process can drive the browser while ZShot runs. `--cdp` must bind a loopback address; another address exits with code 3.

## Example

Serve on port 9222:

**CLI**

```sh
zshot --cdp 127.0.0.1:9222 --cdp-webdriver
```

Run a Selenium script against ZShot, with `capture.py`:

```python
import os

from selenium import webdriver

options = webdriver.ChromeOptions()
options.debugger_address = os.environ["ZSHOT_DEBUGGER_ADDRESS"]
driver = webdriver.Chrome(options=options)
driver.get("https://zshot-cli.com/example_assets/hello_zshot/")
driver.save_screenshot("hello.png")
print(driver.title)
driver.quit()
```

**CLI**

```sh
zshot --cdp --cdp-webdriver -- python capture.py
```

## Related

Flags:

- [`--cdp`](https://zshot-cli.com/reference/flags/server/cdp/)

Topics:

- [ChromeDriver capabilities](https://developer.chrome.com/docs/chromedriver/capabilities) — goog:chromeOptions.debuggerAddress
- [Chrome for Testing](https://googlechromelabs.github.io/chrome-for-testing/) — chromedriver builds by version

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