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webapp-testing

Webapp Testing

Webapp Testing is Anthropic's open-source agent skill for testing local web apps: the agent writes Python Playwright scripts that click through your app, take screenshots and read console logs.

Agent skill by Anthropic Official · Updated

Install Webapp Testing

In Claude Code, add Anthropic's skills marketplace

Terminal
/plugin marketplace add anthropics/skills

Then install the example-skills plugin, which holds this skill and Anthropic's other example skills

Terminal
/plugin install example-skills@anthropic-agent-skills

Or install only this skill, for any agent, with the skills CLI

Terminal
npx skills add anthropics/skills --skill webapp-testing

In Claude.ai, Anthropic says its example skills are already available on paid plans: switch them on under Customize > Skills.

Or paste this into your coding agent: Install the agent skill webapp-testing from github.com/anthropics/skills. A skill can include scripts that run on your computer, so read its source first.

What Webapp Testing does

Webapp Testing is an Anthropic skill for interacting with and testing web applications running on your own machine. It loads when you want to verify that a frontend works, debug UI behavior, capture browser screenshots or read browser logs. The agent writes native Python Playwright scripts that launch Chromium in headless mode.

A decision tree in Webapp Testing picks the approach. For a static HTML file, the agent reads the file to find selectors. For a dynamic app it uses reconnaissance then action: open the page, wait until network activity settles, take a screenshot or inspect the DOM, then act on the selectors it found. The skill flags one common mistake: inspecting a dynamic page before it has finished loading.

A helper script bundled with Webapp Testing starts one or more servers, such as a backend and a frontend, waits until each port answers, runs your test script and then cleans up. The agent runs it with --help and uses it as a black box instead of reading its source. Example scripts show how to find buttons, links and inputs, automate a local HTML file and capture console logs.

When to use Webapp Testing

  • You changed a frontend and want an agent to click through it and confirm it still works.
  • You have a UI bug that only shows up in the browser and want screenshots and console logs to debug it.
  • Your app needs a backend and a frontend running at the same time before it can be tested.

When to pick something else

  • You want UI code reviewed for accessibility and UX rules without running the app: use Web Design Guidelines.

Which agents Webapp Testing works in

Anthropic documents Webapp Testing for Claude Code, Claude.ai, Claude API. The open skills CLI also installs it into 78 agents, including Claude Code, Codex, Cursor, Gemini CLI, GitHub Copilot, OpenCode (we listed it with the CLI on October 1, 2026). See where each agent looks for skills.

Webapp Testing license

Webapp Testing is published under Apache-2.0. Apache-2.0 comes from the LICENSE.txt in the skill's own folder (read 2026-10-01); the anthropics/skills repository has no root license file. In practice you may use, change and share the skill in any agent, commercially too, as long as you keep the license text and notices and mark your changes.

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Lists that include webapp-testing