Argos vs Loki

Argos is a visual testing platform that stores screenshots uploaded by a team's test suite, compares them across builds, and supports review of visual changes. Argos does not connect to applications to capture screenshots. It can also diff Markdown, JSON, HTML, CSS, JavaScript, XML, YAML, and plain text. Integrations include Playwright, Cypress, Storybook, WebdriverIO, its CLI, or any framework, alongside GitHub Actions and deployment providers such as Vercel, Netlify, and Cloudflare. Teams can connect GitHub, GitLab, Slack, Discord, and Microsoft Teams. For agent workflows, Argos offers a remote MCP server, CLI workflows, and a REST API for inspecting diffs, reviewing builds, collaborating, and deploying previews. The Hobby Plan is free, billed forever, and includes up to 5,000 screenshots with 30-day retention. Pro costs $100 a month, billed monthly based on usage, and includes 35,000 screenshots and one-year retention. Argos says its SDKs and platform are open source and MIT-licensed, and that it is SOC 2 Type II and GDPR compliant.

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.