Loki vs Vizzy
Loki
loki.js.orgVizzy
github.comSide by side
| Figure | Loki | Vizzy |
|---|---|---|
| Price from | Free | — |
| Free plan | Yes | — |
| Free trial | — | — |
| Open source | — | — |
| Web | Yes | Yes |
| Windows | Yes | — |
| macOS | Yes | — |
| Linux | Yes | Yes |
| iOS | Yes | — |
| Android | Yes | — |
| Self-hosted | Yes | Yes |
| Plans published | 1 | 0 |
| Spec score · Visual Regression Testing Software | 8.6 (#4) | 6.8 (#23) |
| Image comparison | Loki documents pixelmatch, GraphicsMagick, and looks-same as image comparison engines. | It compares matching screenshots pixel by pixel and generates a third image that highlights differences in red. |
| License | The project repository identifies Loki as MIT licensed. | The repository identifies Vizzy as MIT licensed. |
| Purpose | Loki tests Storybook projects for visual regressions by comparing screenshots with reference images. | Vizzy is a Ruby on Rails web server for visual automation that compares screenshots to help prevent visual regressions. |
| Support | The project provides documentation and a GitHub repository for its community and development. | The README invites developers to join the Vizzy developer Slack community. |
Plans
In their own words
Loki
Loki is a free, MIT-licensed tool for checking Storybook projects for visual regressions. It captures story screenshots and compares them with reference images, producing visual differences for review. The workflow is to create reference screenshots, run comparisons, review the differences, and approve updated references. Loki is designed for continuous integration, where tests can fail if reference images are missing. Capture targets include Chrome in Docker or locally, Chrome in AWS Lambda, the iOS simulator, and the Android emulator; an AWS Lambda renderer is available for large test suites. Node 16 or later is required. Recent Storybook versions need no extra integration for non-React Native projects, while React Native setup uses an import in `storybook/storybook.js`. Projects can configure Loki in a `package.json` section or supported Loki configuration files. Loki does not start Storybook or simulator and emulator servers, so they need to be running before tests. Documented animation limitations include looping requestAnimationFrame animations, GIFs, SVG animations, native Lottie animations, and React Native Animated.