Setting a user agent

The User-Agent request header is a characteristic string that lets servers and network peers identify the application, operating system, vendor, and/or version of the requesting user agent.

Many sites use this information to render the site differently for each user, and sometimes even for rudimentary bot detection. If you run chrome headless and want to take a screenshot of a page, it's a good idea to set a user agent so that web fonts load properly.

note

If you are having trouble getting past bot detectors, we would recommend trying BrowserQL.

Using a Library

You can set the user agent from code, in puppeteer it would be like this:

import puppeteer from "puppeteer";

const browser = await puppeteer.connect({
  browserWSEndpoint: `wss://production-sfo.browserless.io?token=GOES-HERE`,
});
const page = await browser.newPage();
await page.setUserAgent(
  "Mozilla/5.0 (Macintosh; Intel Mac OS X 10_14_0) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/84.0.4147.125 Safari/537.36",
);

REST API

If you're using our APIs like /screenshot, /content, /pdf, or /scrape, you can also set the user agent in the body of your request.

// /content API
{
  "url": "https://example.com/",
  "userAgent": "Mozilla/5.0 (Macintosh; Intel Mac OS X 14_3_1) AppleWebKit/605.1.15 (KHTML, like Gecko) Version/17.3.1 Safari/605.1.15"
}

As launch arg

If you're on a usage-based, cloud unit-based or capacity-based account, you can change the user agent as so

import puppeteer from "puppeteer-core";

const launchArgs = JSON.stringify({
  args: [
    `--user-agent=Mozilla/5.0 (Macintosh; Intel Mac OS X 10_14_6) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/100.0.4896.127 Safari/537.36`,
  ],
});

const browser = await puppeteer.connect({
  browserWSEndpoint: `wss://production-sfo.browserless.io/?token=GOES-HERE&launch=${launchArgs}`,
});