BackstopJS

What BackstopJS is

BackstopJS is a free, MIT-licensed tool for automating visual regression checks on web apps. It captures screenshots and compares them with reference images so teams can inspect visual changes. Its in-browser report presents the reference, test capture, and difference, with CLI and JUnit reports also available. It supports Puppeteer and Playwright; Playwright can use Chromium, Firefox, or WebKit. Test scenarios can script clicks, scrolling, hovering, key presses, and cookie state. Captures can cover a full document, a viewport, or selected DOM elements at configured sizes. The workflow uses `backstop init` to configure a project, `backstop test` to compare screenshots, and `backstop approve` to update reference images. Install it globally or locally with npm, run it as a CLI, or require it from a Node.js app. It can report to CI and integrate with build systems such as Jenkins, Travis, and gulp. A Docker option aims to reduce rendering differences, though Chrome Headless in Docker may time out without substantial memory.