Telescope is a tool designed for cross-browser performance testing. It operates by loading a specified URL in a chosen browser, collecting various performance metrics, and storing the results in a structured format within a designated results directory. Each test creates a folder named with a date and a unique ID, containing files like `console.json` for JavaScript errors, `metrics.json` for timing data, and `screenshot.png` for the final page image. Users can customize tests through a variety of parameters. The tool supports multiple browsers, including Chrome, Firefox, Safari, and Edge, and offers options for setting custom headers, cookies, and throttling conditions. For instance, you can disable JavaScript during tests or specify a timeout period. The command-line interface allows for detailed configurations, such as blocking specific domains or overriding hostnames. To run Telescope, you first need to install its dependencies and build the project. It uses Playwright to control browsers and requires manual installation for some browsers, like Microsoft Edge and Chrome Beta. The tool also relies on `ffmpeg` for video processing, which needs to be installed separately. Once set up, you can execute tests directly from the command line or integrate it into a Node.js script, enabling automated performance checks with ease.