Headless browser sessions let automated tests render and inspect real pages without displaying a Chrome window. Selenium uses the same WebDriver APIs in headless and visible sessions, which makes the mode suitable for CI jobs and remote hosts without a desktop session.

Unified Chrome Headless uses the regular browser engine when --headless is passed through ChromeOptions. An explicit window size keeps responsive breakpoints and element geometry consistent between runs.

The sample loads a local HTML fixture, so its result does not depend on DNS or a public website. Selenium Manager can resolve a compatible driver when needed; runners with pinned browser packages can instead provide ChromeDriver on PATH.

Related: How to install Selenium WebDriver for Python
Related: How to configure ChromeDriver for Selenium
Related: How to use explicit waits in Selenium

Steps to run a headless browser in Selenium:

  1. Create headless-page.html with content that the headless session can verify.
    headless-page.html
    <!doctype html>
<html lang="en">
  <head>
    <meta charset="utf-8">
    <title>Selenium headless demo</title>
  </head>
  <body>
    <h1 id="status">Headless browser ready</h1>
  </body>
</html>
  2. Create selenium-headless-browser-run.py with the fixture URL and Chrome headless options.
    selenium-headless-browser-run.py
    from pathlib import Path
from shutil import which
 
from selenium import webdriver
from selenium.webdriver.chrome.service import Service
from selenium.webdriver.common.by import By
 
 
page_url = (Path(__file__).parent / "headless-page.html").as_uri()
browser_path = which("google-chrome") or which("chromium")
driver_path = which("chromedriver")
 
options = webdriver.ChromeOptions()
options.add_argument("--headless")
options.add_argument("--window-size=1280,720")
if browser_path:
    options.binary_location = browser_path

    The --no-sandbox flag disables a browser security boundary and is not required for headless mode on a normal runner.

  3. Append the browser session and page assertions below the options block. 
    service = Service(driver_path) if driver_path else Service()
driver = webdriver.Chrome(service=service, options=options)
try:
    driver.get(page_url)
    heading = driver.find_element(By.ID, "status").text
    window_size = driver.get_window_size()
 
    assert driver.title == "Selenium headless demo"
    assert heading == "Headless browser ready"
 
    print(f"title: {driver.title}")
    print(f"heading: {heading}")
    print(f"window_size: {window_size['width']}x{window_size['height']}")
    print(f"browser: {driver.capabilities['browserName']}")
finally:
    driver.quit()
  4. Run the completed script to confirm that Chrome renders the fixture without a visible window. 
    $ python3 selenium-headless-browser-run.py
title: Selenium headless demo
heading: Headless browser ready
window_size: 1280x720
browser: chrome