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21st AI

Category: Dev Tools  ·  Sub-category: cli-builders  ·  Last updated:
type:review
Generate and iterate on UI with 21st AI from the terminal via the `21st` CLI (`@21st-dev/cli`): sketch a UI from a prompt, preview the variants in the browser, edit any variant in place with a natural-language change, and pull the final code into the project. Use whenever the user wants to BUILD / SKETCH new UI ("sketch a pricing page", "generate a hero with 21st", "make me a <X> section"), ITERATE on a generated draft ("edit the third variant", "add a toggle to that take"), or GRAB the code of a draft ("pull that variant's code", "сгенери UI на 21st", "поправь третий вариант", "забери код того наброска"). For finding/installing existing components use the `21st-cli-use` skill; to publish your own, `21st-registry`.
Security AStatic scan found no risk patternsHow grading works ›

From the source SKILL.md

21st AI is a fast UI-drafting board. Mental model: draft it here, then finish it — sketch a few variants from a prompt, preview them, refine the one you like with plain-English edits, and pull its code into the repo. The whole loop runs from the 21st CLI (or the matching MCP tools), so you never leave the editor.

What this skill does

21st AI is a community-contributed Claude Code skill in the cli-builders sub-category. It ships as a SKILL.md file that Claude Code auto-discovers under ~/.claude/skills/21st-ai/ and loads when your prompt matches the skill's trigger.

When to invoke it: Use whenever the user wants to BUILD / SKETCH new UI ("sketch a pricing page", "generate a hero with 21st", "make me a <X> section"), ITERATE on a generated draft ("edit the third variant", "add a toggle to that take"), or GRAB the code of a draft ("pull that variant's code", "сгенери UI на 21st", "поправь третий вариант", "забери код того наброска"). For finding/installing existing components use the `21st-cli-use` skill; to publish your own, `21st-registry`.

Who uses this skill

The 21st AI Claude Code skill is built for developers, power users, and teams automating repetitive workflows and improving developer experience. It's part of ClaudSkills (also referred to as Claude Skills or Claude Code Skills) — the open community-curated registry of 161,000+ SKILL.md files for Anthropic's Claude Code agent and the wider Claude ecosystem (Claude API, Claude Agent SDK).

How to install

Free

Manual install (2 steps)

mkdir -p ~/.claude/skills/21st-ai
curl -L https://claudskills.com/skills/21st-ai/SKILL.md \
  -o ~/.claude/skills/21st-ai/SKILL.md

Or just download SKILL.md directly and drop it into ~/.claude/skills/21st-ai/. Claude Code auto-discovers it on next session.

Skills live at ~/.claude/skills/21st-ai/SKILL.md on macOS/Linux, or %USERPROFILE%\.claude\skills\21st-ai\SKILL.md on Windows. See the full install guide for step-by-step instructions.

Telegram

📱 Install from your phone or desktop Telegram

Open @claudskills_bot on Telegram, tap Open Desktop App, and the desktop app installs this skill for you. Or share the bot link with a colleague — they get the same one-tap install. Learn more →

Pro

One-click install via the desktop app

The ClaudSkills desktop app installs any skill directly into ~/.claude/skills/ with one click — no terminal required. Pro starts at $9/mo or $149 lifetime.

Pro

For the full experience including quality scoring and one-click install features for each skill — upgrade to Pro.

See pricing → Download desktop app

Frequently asked questions

How do I install the 21st AI Claude Code skill?
Install via the ClaudSkills desktop app (one click) or copy SKILL.md from the source repository to ~/.claude/skills/21st-ai/SKILL.md and restart Claude Code. Both flows are detailed at claudskills.com/install/.
What does the 21st AI skill do?
Generate and iterate on UI with 21st AI from the terminal via the `21st` CLI (`@21st-dev/cli`): sketch a UI from a prompt, preview the variants in the browser, edit any variant in place with a natural-language change, and pull the final code into the project. Use whenever the user wants to BUILD / SKETCH new UI ("sketch a pricing page", "generate a hero with 21st", "make me a <X> section"), ITERATE on a generated draft ("edit the third variant", "add a toggle to that take"), or GRAB the code of a draft ("pull that variant's code", "сгенери UI на 21st", "поправь третий вариант", "забери код того наброска"). For finding/installing existing components use the `21st-cli-use` skill; to publish your own, `21st-registry`.
Is this skill free to install?
Yes. ClaudSkills is an open registry — every skill keeps its source repository's license, and manual install via copy is free. ClaudSkills Pro ($9/mo, $79/yr, or $149 one-time) adds one-click install via the desktop app and a multi-signal Quality Score.
When should I use the 21st AI skill?
Use 21st AI when your Claude Code task falls under the Dev Tools category — specifically in the cli builders area. Claude Code auto-discovers installed skills and invokes the right one based on the task description, so you can also ask Claude directly (e.g. "use 21st AI" or describe the task and let Claude pick). Browse related skills at /category/tools/.
What is a Claude Code skill and how does the 21st AI skill fit in?
A Claude Code skill is a SKILL.md file that lives under ~/.claude/skills/<name>/ and tells the Claude Code CLI agent how to perform a specific task (instructions, prompts, allowed tools). Skills are auto-discovered at session start. 21st AI is one of 67,000+ skills indexed in the open ClaudSkills catalog, classified under the Dev Tools category. Learn more at /learn/what-is-a-claude-skill/.

Attribution & license

Cite this skill

If you reference this skill in a blog post, paper, or documentation, you can cite it as:

APA
21st-dev. (2026). 21st AI [Claude Code skill]. ClaudSkills. https://claudskills.com/skills/21st-ai/
BibTeX
@misc{21st-ai-2026,
  author    = {21st-dev},
  title     = {21st AI [Claude Code skill]},
  year      = {2026},
  publisher = {ClaudSkills},
  url       = {https://claudskills.com/skills/21st-ai/}
}

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Security scan

Grade A · scanned 2026-07-27 — free static scan against the OWASP Agentic Skills Top 10.

No risk patterns were found in any of the ten OWASP-aligned categories. How grading works ›

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