Puppeteer is a Node.js library from Google that gives you programmatic control over Chrome or Firefox browsers.

It runs headless by default (no visible browser window), but you can watch it work in headed mode for debugging. You write JavaScript to tell it what to do: click buttons, fill forms, take screenshots, generate PDFs, or scrape data.

Most builders use it for web scraping, automated testing, and generating static content from dynamic pages. It's particularly good at handling JavaScript-heavy sites that traditional scrapers can't touch. Popular for building bots that need to interact with websites like a real user would.

Free and open source. Downloaded over 4.5 million times per week. Works with Node.js and integrates with testing frameworks like Jest.