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Create Design Context

From the project root:
This writes .21st/design.json, the machine-readable source of truth, and .21st/DESIGN.md, a readable summary. 21st detects the framework, Tailwind version, shadcn setup, token sources, component folders, installed primitives, assets, and project instruction files. Each inferred fact includes source evidence. Edit constraints.must, constraints.avoid, and decisions in .21st/design.json. Refreshing preserves those user-owned fields:
--check never writes and exits non-zero when extracted project facts drift.

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Find grounded inspiration

Context-aware search returns metadata, confidence, and concrete fit rationales. It does not retrieve metered component code.

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Generate alternatives

Every take receives the same project stack, tokens, primitives, constraints, and accepted decisions. 21st also assigns a distinct named direction and rationale to each take, so variants differ in hierarchy and composition rather than only color. The preview URL remains the place to compare, select, and refine takes.

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Review locally

Review is local and free. It reports deterministic accessibility, interaction, responsive, motion, and design-system findings with file and line attribution. --fix only applies high-confidence mechanical fixes. Suppress a rule only with a reason:

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Manage skills

Project-local installation is the default:
Add --global for a user-wide installation and --agent claude|cursor|codex|all to select harnesses. 21st verifies each skill hash, records ownership and license metadata in .21st/skills.lock, and refuses to overwrite or remove local modifications without --force. 21st install-skill remains a compatibility alias for 21st skills install --global.

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Curated external skills

21st does not duplicate the general skill marketplace. Browse the small reviewed compatibility catalog, or use skills.sh for broad discovery:
An external install is always project-local and explicit. Skills containing scripts require a second consent flag:
21st pins the installer version, verifies the allowlist entry, inspects the installed file tree, records scripts/capabilities/license/source in the lockfile, and refuses silent global installation. It never combines external instructions with first-party skills automatically.