Network log capture in Selenium Python

Introduction

Network log capture helps you see what data your browser sends and receives during testing. It shows requests and responses, so you can check if your app talks to servers correctly.

You want to check if a web page loads all images and scripts properly.

You need to verify that API calls return the right data during a test.

You want to find out why a page is slow by looking at network requests.

You want to confirm that sensitive data is not sent over insecure connections.

Syntax

Selenium Python

from selenium import webdriver
from selenium.webdriver.chrome.service import Service
from selenium.webdriver.chrome.options import Options
from selenium.webdriver.common.desired_capabilities import DesiredCapabilities

caps = DesiredCapabilities.CHROME.copy()
caps['goog:loggingPrefs'] = {'performance': 'ALL'}

options = Options()
service = Service('/path/to/chromedriver')
driver = webdriver.Chrome(service=service, options=options, desired_capabilities=caps)

# After loading a page
logs = driver.get_log('performance')

Use desired_capabilities to enable performance logging in Chrome.

Logs contain network events in JSON format inside the 'message' field.

Examples

This sets Chrome to capture all performance logs, including network events.

Selenium Python

caps = DesiredCapabilities.CHROME.copy()
caps['goog:loggingPrefs'] = {'performance': 'ALL'}

This retrieves and prints all performance log messages from the browser.

Selenium Python

logs = driver.get_log('performance')
for entry in logs:
    print(entry['message'])

Sample Program

This script opens a browser, navigates to example.com, captures network responses, and prints each URL with its HTTP status code.

Selenium Python

from selenium import webdriver
from selenium.webdriver.chrome.service import Service
from selenium.webdriver.chrome.options import Options
from selenium.webdriver.common.desired_capabilities import DesiredCapabilities
import json

caps = DesiredCapabilities.CHROME.copy()
caps['goog:loggingPrefs'] = {'performance': 'ALL'}

options = Options()
service = Service('/path/to/chromedriver')
driver = webdriver.Chrome(service=service, options=options, desired_capabilities=caps)

try:
    driver.get('https://example.com')
    logs = driver.get_log('performance')
    network_events = []
    for entry in logs:
        message = json.loads(entry['message'])['message']
        if 'Network.responseReceived' == message['method']:
            url = message['params']['response']['url']
            status = message['params']['response']['status']
            network_events.append(f"URL: {url}, Status: {status}")
    for event in network_events:
        print(event)
finally:
    driver.quit()

Important Notes

Make sure to use the correct path to your ChromeDriver in Service.

Network logs can be large; filter them to find useful info.

Not all browsers support performance logging the same way; Chrome is recommended.

Summary

Network log capture lets you see browser-server communication during tests.

Enable performance logging in Chrome to get network events.

Parse logs to check URLs and response status codes for validation.