21st-ai

Original：🇺🇸 English

Translated

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`.

4installs

Source21st-dev/skill

Added on2026-08-14

NPX Install

npx skill4agent add 21st-dev/skill 21st-ai

SKILL.md Content

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21st AI — sketch, iterate & grab code from the terminal

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.

Sketch mode produces self-contained HTML + Tailwind drafts (fast, no build). The recommended handoff is the copy-prompt: a spec that tells you to rebuild the design in the target project's real stack — not paste raw HTML verbatim.

Auth

Same credential as the rest of the CLI:

21st login

(saved token) or a

21st_sk_

key via

--api-key

/

TWENTYFIRST_TOKEN

.

21st usage

shows tier + remaining quota. (See the

21st-cli-use

skill for the full auth notes.)

The loop

bash

# 1) Sketch — generate variants ("takes") from a prompt. Opens the preview in
#    the browser and prints the projectId.
21st generate "a pricing section with 3 tiers and a monthly/annual toggle"

# 2) List the takes (1-based numbers + whether each has rendered yet).
21st generation <projectId>

# 3) Edit ONE take in place with a natural-language change (PAID — see Metering).
21st iterate <projectId> "make it enterprise-flavored, add an annual toggle" --take 3

# 4) Grab the code to bring into the project (FREE).
21st take <projectId> --take 3            # paste-ready copy-prompt (recommended)
21st take <projectId> --take 3 --code     # raw self-contained HTML instead

Open the preview URL (printed by

generate

, and returned by

iterate

) in the editor's built-in browser to watch the variants render and update in place.

When to use which

generate — start fresh from a prompt. Returns a preview URL + projectId.
generation — list the takes so you know which
```
--take N
```
to act on.
iterate — refine an EXISTING take (edited in place; a new version is appended, so you can step back in the workspace). Use this to change something already generated instead of starting over.
take — pull a take's code. Default prints the copy-prompt (adapt-to-my- stack spec);
```
--code
```
prints the raw HTML. Both FREE and unlimited.

Metering

generate — small free daily bucket, then a paywall (
```
21st usage
```
shows what's left). Community access / membership lifts it.
iterate — billed by real token cost per edit (the shared 21st AI credit pool); it does real model work each call, so batch changes into one clear instruction rather than many tiny ones.
generation (listing) and take (grabbing code) are FREE.

MCP parity

The same loop is exposed as MCP tools for MCP hosts (Cursor, Claude Desktop, Claude Code):

generate

(with

mode: "sketch"

),

get_generation

,

iterate_generation

and

get_take

.

iterate_generation

also returns the freshly-edited

html

+

copyPrompt

, so you can grab the code without a second call. Wire up the server with

21st init --client <name> --write

.

Tips

A sketch is a draft, not production code — treat the copy-prompt as a design spec and rebuild it in the project's real components; don't paste the HTML as-is.
Refer to takes by the 1-based number from
```
generation
```
/ the "Take N" label in the preview.
```
--take
```
must be a whole number ≥ 1 (a bad value errors rather than silently editing take 1).
Only sketch generations you created can be listed, edited, or fetched.