webapp-testing Skill

webapp-testing is a skill in Anthropic's anthropics/skills repository that teaches Claude to test web applications running on your own machine. Claude writes native Python Playwright scripts, launches Chromium headless, waits for the network to go idle, then inspects the rendered page, takes screenshots and reads console logs. A helper, scripts/with_server.py, starts one or more servers first, for example python scripts/with_server.py --server "npm run dev" --port 5173 -- python your_automation.py, and the examples folder covers finding elements, static HTML and console logging. In Claude Code, add the repository as a marketplace with /plugin marketplace add anthropics/skills, then install the set that contains it with /plugin install example-skills@anthropic-agent-skills. After that, asking Claude to check that a page works is enough for it to pick the skill up. We find it useful right after a UI change, when the question is whether the page actually renders and responds rather than whether the code compiles. Having Claude click through the flow and hand back a screenshot is a quicker check than describing the bug in words. A caution: the scripts are Python and use Playwright's Python library, so the machine needs both, and the skill is written for local apps rather than for a deployed site behind a login. The repository also states its skills are for demonstration and educational purposes, so treat it as a starting point rather than a test suite.