Modify HTTP Headers in Web Automation Using Requestly Interceptor

In this guide, we’ll walk through how to integrate Requestly Interceptor into any browser-based automation framework (Selenium, Playwright, Puppeteer, etc.) to programmatically modify request and response headers.

Steps to Use Requestly Interceptor for Header Modification in Automation

We also offer an NPM package, @requestly/rq-automation, to make this easier.
Learn more →

Install Chrome for Testing

Download Chrome for Testing, the automation-friendly version of Chrome.

Why Chrome for Testing?Starting with Chrome 137, official Chrome builds no longer support the --load-extension flag due to security concerns. There commit →To load extensions in automation tools (Selenium, Playwright, Puppeteer, etc.), you must use Chrome for Testing or Chromium.Regular Chrome will block extension loading via automation. Use Chrome for Testing to avoid breakages and ensure compatibility.

Install the Automation Tool of Your Choice

Selenium
Playwright
Puppeteer

npm install selenium-webdriver

npm install playwright

npm install puppeteer

Download the Requestly Interceptor CRX Extension

If you’re using our NPM package, you don’t need to download it. Simply call the function getExtension().

Download the CRX file of the Requestly Interceptor Extension.

Configure the Browser with the Extension

Use your automation tool’s configuration options to:

Set the path to Chrome for Testing binary
Add the Requestly Interceptor CRX extension

For JavaScript, use our NPM package @requestly/rq-automation.
Learn more →

Selenium
Playwright
Puppeteer

For Javascript ( Node.js )

const { Builder } = require("selenium-webdriver");
const chrome = require("selenium-webdriver/chrome");
const path = require("path");
const extensionPath = path.resolve(__dirname, 'requestly.crx'); // unpacked CRX folder

// IF Using Our NPM Package @requestly/rq-automation
// const { getExtension } = require("@requestly/rq-automation");
// const extensionPath = getExtension("crx");
// -----

const options = new chrome.Options();
options.setChromeBinaryPath("/Path/to/chrome-for-testing"); 
options.addExtensions(extensionPath);  

const driver = await new Builder()
  .forBrowser("chrome")
  .setChromeOptions(options)
  .build();
// Now use driver.get() to navigate as needed...

For Python

from selenium import webdriver
from selenium.webdriver.chrome.options import Options

chrome_options = Options()
chrome_options.binary_location = "/Path/to/chrome-for-testing"
chrome_options.add_extension("/path/to/requestly.crx")

driver = webdriver.Chrome(options=chrome_options)
# driver.get(...) to open pages

For Java

ChromeOptions options = new ChromeOptions();
options.setBinary("/Path/to/chrome-for-testing");
options.addExtensions(new File("/path/to/requestly.crx"));
WebDriver driver = new ChromeDriver(options);
// driver.get(...) to open pages

For Javascript ( Node.js )

const { chromium } = require('playwright');
const extensionPath = require('path').resolve(__dirname, 'requestly'); // unpacked CRX folder

// IF Using Our NPM Package @requestly/rq-automation
// const { getExtension } = require("@requestly/rq-automation");
// const extensionPath = getExtension("unpacked");
// -----

const userDataDir = './user-data';

const context = await chromium.launchPersistentContext(userDataDir, {
  channel: "chromium", // Enable extensions
  headless: false, // Set to true only if you handle '--headless=new'
  args: [
      `--disable-extensions-except=${extensionPath}`,
      `--load-extension=${extensionPath}`,
    ],
  });

const page = await context.newPage();
// Use page.goto(...) next

For Python

from playwright.sync_api import sync_playwright

path_to_ext = "./requestly"   # path to unpacked CRX folder
user_data_dir = "/tmp/user-data-dir"

with sync_playwright() as pw:
    context = pw.chromium.launch_persistent_context(
        user_data_dir,
        channel="chromium",
        headless=False,
        args=[
            f"--disable-extensions-except={path_to_ext}",
            f"--load-extension={path_to_ext}"
        ]
    )
    page = context.new_page()
    # use page.goto(...)
    context.close()

For Javascript ( Node.js )

const puppeteer = require('puppeteer');
const path = require('path');
const extensionPath = path.resolve(__dirname, 'requestly'); 

// IF Using Our NPM Package @requestly/rq-automation
// const { getExtension } = require("@requestly/rq-automation");
// const extensionPath = getExtension("unpacked");
// -----

const browser = await puppeteer.launch({
  executablePath: "/Path/to/chrome-for-testing",
  headless: false,
  args: [
    `--disable-extensions-except=${extensionPath}`,
    `--load-extension=${extensionPath}`
  ]
});
const page = await browser.newPage();
// page.goto(...) next

Close Extension Welcome Page

When Chrome installs the Requestly Interceptor extension, it may open a “welcome” (post-install) tab that interrupts automation. You can close this tab programmatically:

Selenium
Playwright
Puppeteer
With NPM Package

  // give Chrome a moment for any stray tabs
  await driver.sleep(500);

  // close any “welcome” tab if still present
  const handles = await driver.getAllWindowHandles();
  const mainHandle = handles[0];
  for (const handle of handles.slice(1)) {
    await driver.switchTo().window(handle);
    await driver.close();
  }
  await driver.switchTo().window(mainHandle)

  const page = await context.newPage(); // Assume the first one is your primary page
  await page.waitForTimeout(2000);
  // Get all open pages in the current context
  const pages = context.pages();
  // Iterate through the pages and close any that are not the primary 'page' object
  for (const openedPage of pages) {
    if (openedPage !== page) {
      console.log(`Closing extraneous page: ${openedPage.url()}`);
      await openedPage.close();
    }
   }
  // page.goto(...) next

  const pages = await browser.pages();
  const page = pages[0]; // Assume the first one is your primary page

  await page.waitForTimeout(2000);

  // Close all other pages except the primary one
  for (const openedPage of pages) {
    if (openedPage !== page) {
      console.log(`Closing extraneous page: ${openedPage.url()}`);
      await openedPage.close();
    }
  }

// FOR SELENIUM ONLY
const { closeWelcomePage } = require("@requestly/rq-automation");
await closeWelcomePage(driver);

Perform Header Modifications Using Automation URLs

Once the browser is launched with Requestly Interceptor, hit the following URLs to programmatically apply rules:

Normal way
NPM package

Add Request Header

To add multiple headers, simply append them using the & symbol like this:
?header1=value1&header2=value2&header3=value3

https://app.requestly.io/automation/add-request-header?<headerName>=<headerValue>

Add Response Header

https://app.requestly.io/automation/add-response-header?<headerName>=<headerValue>

Remove Request Headers

To remove multiple headers, simply append them using the & symbol like this:
?header1&header2&header3

https://app.requestly.io/automation/remove-request-header?<headerName>

Remove Response Headers

https://app.requestly.io/automation/remove-response-header?<headerName>

const {
  addRequestHeaderUrl,
  addRequestHeadersUrl,
  removeRequestHeaderUrl,
  removeRequestHeadersUrl,
  addResponseHeaderUrl,
  addResponseHeadersUrl,
  removeResponseHeaderUrl,
  removeResponseHeadersUrl,
} = require("@requestly/rq-automation");

 // Add a single request header
  await driver.get(addRequestHeaderUrl("X-Custom-Header", "MyValue"));

  // Add multiple request headers
  await driver.get(
    addRequestHeadersUrl({
      Authorization: "Bearer token123",
      "X-Another-Header": "AnotherValue",
    })
  );

  // Remove a request header
  await driver.get(removeRequestHeaderUrl("X-Another-Header"));

  // Remove multiple request headers
  await driver.get(
    removeRequestHeadersUrl(["Authorization", "X-Custom-Header"])
  );

  // Add a response header
  await driver.get(addResponseHeaderUrl("Access-Control-Allow-Origin", "*"));

  // Add multiple response headers
  await driver.get(
    addResponseHeadersUrl({
      "X-Response-Header": "ResponseValue",
      "X-Another-Response-Header": "AnotherResponseValue",
    })
  );

  // Remove a response header
  await driver.get(removeResponseHeaderUrl("X-Another-Response-Header"));

  // Remove multiple response headers
  await driver.get(
    removeResponseHeadersUrl(["X-Response-Header", "X-Another-Response-Header"])
  );

Test on a Live Site

To verify if the headers are successfully modified, open https://testheaders.com in the automated browser and inspect the headers shown.You may need to trigger a button click to reveal headers on some pages.

Complete Working Example in Selenium ( Javascript )

Here’s a working example using Selenium, but this logic can be adapted easily to Playwright, Puppeteer, or others.

Normal way
NPM package

const { Builder, By, until } = require("selenium-webdriver");
const chrome = require("selenium-webdriver/chrome");
const path = require("path");

(async () => {
  const options = new chrome.Options();

  options.setChromeBinaryPath("/Path/to/chrome-for-testing");
  options.addExtensions(path.resolve(__dirname, "requestly.crx"));

  const driver = await new Builder()
    .forBrowser("chrome")
    .setChromeOptions(options)
    .build();
  
  // give Chrome a moment for any stray tabs
  await driver.sleep(500);

  // close any “welcome” tab if still present
  const handles = await driver.getAllWindowHandles();
  const mainHandle = handles[0];
  for (const handle of handles.slice(1)) {
    await driver.switchTo().window(handle);
    await driver.close();
  }
  await driver.switchTo().window(mainHandle)

  try {
    await driver.get("https://app.requestly.io/automation/add-request-header?x-testing=selenium");

    await driver.wait(
      until.elementTextContains(
        driver.findElement(By.tagName("body")),
        "Success"
      ),
      1000
    );

    await driver.get("https://testheaders.com");

    await driver.findElement(By.css("button")).click();

    await driver.wait(
      until.elementTextContains(
        driver.findElement(By.tagName("body")),
        "x-testing"
      ),
      5000
    );

    console.log("Header added and verified!");

  } catch (err) {
    console.error("Error during automation:", err);
  } finally {
    await driver.quit();
  }
})();

const {
  addRequestHeaderUrl,
  addRequestHeadersUrl,
  removeRequestHeaderUrl,
  removeRequestHeadersUrl,
  addResponseHeaderUrl,
  addResponseHeadersUrl,
  removeResponseHeaderUrl,
  removeResponseHeadersUrl,
  importRules,
  closeWelcomePage,
} = require("@requestly/rq-automation");
const { Builder } = require("selenium-webdriver");
const chrome = require("selenium-webdriver/chrome");
const { getExtension } = require("@requestly/rq-automation");

async function setupDriver() {
  const options = new chrome.Options();

  // Load Requestly Interceptor extension
  const extensionPath = getExtension("unpacked");
  options.addArguments(`--load-extension=${extensionPath}`);
  options.addArguments(`--disable-extensions-except=${extensionPath}`);

  const driver = await new Builder()
    .forBrowser("chrome")
    .setChromeOptions(options)
    .build();

  return driver;
}

async function seleniumExample() {
  const driver = await setupDriver();
  await closeWelcomePage(driver);

  // Add a single request header
  await driver.get(addRequestHeaderUrl("X-Custom-Header", "MyValue"));

  // Add multiple request headers
  await driver.get(
    addRequestHeadersUrl({
      Authorization: "Bearer token123",
      "X-Another-Header": "AnotherValue",
    })
  );

  // Remove a request header
  await driver.get(removeRequestHeaderUrl("X-Another-Header"));

  // Remove multiple request headers
  await driver.get(
    removeRequestHeadersUrl(["Authorization", "X-Custom-Header"])
  );

  // Add a response header
  await driver.get(addResponseHeaderUrl("Access-Control-Allow-Origin", "*"));

  // Add multiple response headers
  await driver.get(
    addResponseHeadersUrl({
      "X-Response-Header": "ResponseValue",
      "X-Another-Response-Header": "AnotherResponseValue",
    })
  );

  // Remove a response header
  await driver.get(removeResponseHeaderUrl("X-Another-Response-Header"));

  // Remove multiple response headers
  await driver.get(
    removeResponseHeadersUrl(["X-Response-Header", "X-Another-Response-Header"])
  );

  // Import a shared list of rules
  await driver.get(importRules("YOUR_API_KEY"));

  // Your test code here
  await driver.get("https://example.com");

  await driver.quit();
}

seleniumExample();

Getting Started

Debugging & Interception

HTTP Rules

Mock APIs & Responses

Guides

Public APIs

Troubleshoot

Modify HTTP Headers in Web Automation Using Requestly Interceptor

Steps to Use Requestly Interceptor for Header Modification in Automation

Add Request Header

Add Response Header

Remove Request Headers

Remove Response Headers

Complete Working Example in Selenium ( Javascript )

​Steps to Use Requestly Interceptor for Header Modification in Automation

​Add Request Header

​Add Response Header

​Remove Request Headers

​Remove Response Headers

​Complete Working Example in Selenium ( Javascript )

Steps to Use Requestly Interceptor for Header Modification in Automation

Add Request Header

Add Response Header

Remove Request Headers

Remove Response Headers

Complete Working Example in Selenium ( Javascript )