Watchlight

What Watchlight is

Watchlight is a Windows tool for visual regression testing of desktop apps and games. It launches an executable, captures screenshots, and compares changes across snapshots. Captures can happen after a delay or when a configured stdout pattern appears. Comparisons include side-by-side views, multiple diff modes, configurable thresholds, and pass/fail results with diff percentages. A scene uses its configured baseline, or otherwise the first snapshot by name order. Watchlight runs locally without a cloud dependency and lists support for WPF, WinUI, Qt, Electron, Tauri, Unity, and Godot. Its headless CLI can capture and analyze snapshots, produce structured JSON, and use strict mode to return a non-zero exit code when visual diffs fail. A local stdio MCP server connects with AI assistants; setup examples cover VS Code, Cursor, and Claude Code. The site says Watchlight works with any CI system and names GitHub Actions, GitLab, and Jenkins as examples. The Free plan includes the GUI with unlimited projects and scenes. CLI and MCP require Pro after beta; all features are free during beta, and Pro is listed at $9 a month, with annual billing around $86 per year.