DiffiCat vs Happo

DiffiCat compares source and target websites to check page existence, content accuracy, and visual changes during migrations. It checks HTTP status codes, broken redirects, authentication walls, and server errors. Content comparisons cover titles, headings, meta descriptions, and body text, using a 90% word-overlap threshold. For visual regression, it captures full-page screenshots and compares pixels with a configurable threshold that defaults to 0%. Viewport widths can be set to 375px, 768px, or 1440px, or customized from 320px to 2560px. A run can cover up to 10,000 pages; leaving the page limit blank removes the cap on discovered pages. DiffiCat can render JavaScript-driven pages, use HTTP basic authentication for both sites, and capture one or multiple URLs without a second site. Exports are ZIP files containing a plain-text report and PNG screenshots. The desktop app keeps outputs on the user's disk and uploads no URLs or screenshots; browser storage lasts for the browser session. The Free plan costs nothing. Desktop use has no limits for personal use; browser limits apply, and commercial use requires a license.

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.