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Break UI

Break UI is an agent skill (a SKILL.md file) from emilkowalski/skills. Try to break a piece of UI by feeding it worst-case data — long names, unbreakable emails, one-letter names, missing fields, huge counts, zero items, long labels, non-Latin text, emoji… It works with Claude Code and has 49,702 GitHub stars across a repository of 14 listed skills.

github.com/emilkowalski/skills/skills/break-ui (opens in a new tab)

Data as of from the GitHub API and skills.sh; description from the skill's SKILL.md. Report an error

View on GitHub (opens in a new tab)View on skills.sh (opens in a new tab)

Add this skill

Claude

Claude Code loads skills from ~/.claude/skills/ (all projects) or .claude/skills/ (one project):

git clone --depth 1 https://github.com/emilkowalski/skills.git
cp -r skills/skills/break-ui ~/.claude/skills/break-ui   # personal, or .claude/skills in a project

In the Claude apps, zip the break-ui folder and upload it under Customize > Skills > + > Upload a skill (code execution must be on).

ChatGPT / Codex

Codex reads skills from .agents/skills/ in a repo or ~/.agents/skills/ for every project:

git clone --depth 1 https://github.com/emilkowalski/skills.git
cp -r skills/skills/break-ui .agents/skills/break-ui   # repo; ~/.agents/skills for all projects

Standalone skills also load in the ChatGPT desktop app.

Cursor

Cursor loads skills from .cursor/skills/ (or ~/.cursor/skills/) and also reads .claude/skills/:

git clone --depth 1 https://github.com/emilkowalski/skills.git
cp -r skills/skills/break-ui .cursor/skills/break-ui   # project; ~/.cursor/skills for all projects

Source (checked Oct 7, 2026): code.claude.com/docs/en/skills (opens in a new tab), support.claude.com/en/articles/12512180-using-skills-in-claude (opens in a new tab), learn.chatgpt.com/docs/build-skills (opens in a new tab), cursor.com/docs/context/skills (opens in a new tab)

What this skill does

Try to break a piece of UI by feeding it worst-case data — long names, unbreakable emails, one-letter names, missing fields, huge counts, zero items, long labels, non-Latin text, emoji, extreme numbers — then render it behind a "Demo data / Worst case" toggle and report everything that broke, with the fix for each. Use when the user asks to stress-test, break, or find edge cases in a component or screen, or to "try the worst case".

When it triggers

  • Use when the user asks to stress-test, break, or find edge cases in a component or screen, or to "try the worst case".
  • use emil-design-eng; for motion use review-animations.
  • "Demo data / Worst case"
  • "try the worst case"

More skills in emilkowalski/skills

14 skills are listed from this repository.

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FAQ

Break UI FAQ

Still curious? Email info@appsgit.com.

How do I install the Break UI skill?

Copy the break-ui folder (the one containing SKILL.md) into ~/.claude/skills/ for Claude Code, .agents/skills/ for Codex or .cursor/skills/ for Cursor. The agent picks it up automatically when a task matches its description.

Is the Break UI skill free?

Yes. The repository is open source under the MIT license.

Is Break UI maintained?

The repository's most recent commit was on Oct 11, 2026. appsgit only lists skills from repositories with a commit in the last six months.