BackstopJS vs Happo

BackstopJS is a free, MIT-licensed tool for visual regression testing of web applications. It captures screenshots and compares them with reference images over time. An in-browser report shows reference, test and visual-difference views, with additional CLI and JUnit reports. BackstopJS supports Puppeteer and Playwright; Playwright can use Chromium, Firefox or WebKit. Scenarios can script clicks, scrolling, hovering, key presses and cookie state. Captures can cover a full document, viewport or selected DOM elements at configured viewport sizes. The documented workflow uses `backstop init`, `backstop test` and `backstop approve` to configure tests, compare captures and update references. Installation works globally or locally through npm, as a standalone CLI or from a Node.js app. CI reporting and integrations include Jenkins, Travis and gulp. Docker can reduce rendering differences, though Chrome Headless in Docker needs substantial memory.

Happo checks interface changes with visual and accessibility regression testing. It captures screenshots of component variants in browsers; a snapshot is one variant in one browser, and a run usually occurs once per CI build. Accessibility testing is included on every plan. Framework options include Storybook, Playwright, Cypress, and a generic API. Repository integrations include GitHub, GitHub Enterprise, Bitbucket, Azure DevOps, and GitLab, though GitLab support is experimental. Its CLI detects CI providers such as GitHub Actions, CircleCI, Travis CI, and Azure DevOps. Available browsers vary by plan: the listed options are Chrome, Firefox, Safari, Microsoft Edge, and iOS Safari. The free plan includes 5,000 snapshots per month; once the quota is reached, the account pauses until the next cycle or an upgrade. Paid plans start at $149/mo, with additional snapshots charged on paid tiers. Happo began as a project in 2014, and its commercial product launched in 2017.