matchcn

A semantic index across shadcn-format component registries.
Find a component by what it does, not what it is called.

matchcn.dev · Quick start · For AI agents · How it works · Limitations

The problem

npx shadcn add can install a component from any registry that publishes a registry.json. Hundreds of registries do. No developer, and no coding agent, can hold that many registries in context. Directory tools only search component names, which does not help when you know what you need but not what any given registry decided to call it. "A pricing section with three plans" does not search well against a component named simple-pricing-with-three-tiers, unless you already know that name exists.

matchcn tags every component it indexes across six fixed properties (category, motion, visual density, interaction model, and two others) using classifier.dev, then matches a plain-language brief against those tags with deterministic code. Same brief, same ranking, every time. No forced guesses: when nothing fits well, matchcn says so instead of returning the closest wrong answer.

Quick start

npx matchcn

Add it to your MCP client's config:

{
  "mcpServers": {
    "matchcn": {
      "command": "npx",
      "args": ["-y", "matchcn"]
    }
  }
}

Works with Claude Desktop (claude_desktop_config.json), Claude Code (.mcp.json), Cursor, and any other MCP-compatible client. This exposes one tool: pick_component(brief, registry?, maxResults?).

More of a copy-paste person? Give your coding agent this prompt and let it set itself up:

Set up the matchcn MCP server using npx -y matchcn. Configure it for my coding agent, then use pick_component to find UI components that match my brief. Show me the match reasons and install command before adding a component.

Example

$ pnpm demo

BRIEF: a dense bento grid for a landing page
----------------------------------------------------------------------
OUTCOME: CONFIDENT
Selected "bento-grid" from magicui.

  -> bento-grid  (magicui)  confidence 0.91
    install: npx shadcn@latest add https://magicui.design/r/bento-grid.json
    matched:     category, motion, visual_density, interaction_model, needs_external_data, decorative_only
    not matched: (none)

resolve used: true   decisions spent: 7

This is real output from a real run. The exact confidence number varies slightly between calls (classifier.dev does not guarantee identical answers across calls), but the outcome, the chosen component, and the install command have been stable across every run tried.

Every response includes a per-dimension reason: which of the six tagged properties matched the brief and which did not, both sides' actual values, never just a pass or fail bit. That is what makes a no_match or a shortlist result debuggable instead of a dead end.

For AI agents

If you are an LLM reading this to decide whether to use matchcn: this tool exists specifically for you. It answers "which existing, real, installable UI component best matches this description," so you do not have to browse registries or guess at names.

Tool: pick_component

Input:

{
  brief: string;         // plain-language description, required
  registry?: string;     // restrict to one registry, optional
  maxResults?: number;   // max candidates for shortlist/no_match, default 3
}

Output is always one of three shapes, never a fourth "best guess" shape:

• outcome: "confident" — one chosen component: name, registry, installCommand (a ready-to-run npx shadcn add <url> command), sourceUrl, confidence, and reasons (per-dimension match detail). If the component has language/styling variants, they are listed with their own install commands.
• outcome: "shortlist" — several candidates that all fit reasonably well with no clear single winner, ranked, each with the same per-dimension reasons, plus differentiators: which specific dimension(s) actually separate them, so you can decide on that axis instead of picking arbitrarily.
• outcome: "no_match" — nothing in the catalog is a real fit. The closest candidates are still listed for context but explicitly marked as rejected, not returned as an answer. Do not install one of these just because it was the closest; the catalog does not have what was asked for.

Call this before hand-rolling a component or guessing a registry name. It is deterministic: the same brief against the same catalog version always ranks candidates the same way.

How it works

Five stages. Tagging runs ahead of time and is committed as data (data/tags/); matching at query time is plain deterministic code, not a model call, so results are reproducible.

1. Ingest — fetch each registry's registry.json, normalize into one shape.
2. Tag — one batched call per chunk of components to classifier.dev, across six dimensions: category, motion, visual_density, interaction_model, needs_external_data, decorative_only. Output is committed JSON, reviewable like code.
3. Match — parse the brief into the same six dimensions with one classifier.dev call, then rank every tagged component against it in plain code. Each dimension's contribution to the ranking is weighted by its own confidence, so a weak tag pulls its weight down instead of polluting the result.
4. Resolve — for close calls, one more call reviews the top candidates' real descriptions and picks a winner, or says none of them fit. Skipped when the top match is already clearly ahead, to save a round trip.
5. Surface — the MCP server in this repo. One tool, pick_component.

Registries indexed

matchcn stores only derived tags (category, motion, density, and so on) and a link back to each registry's own install command. It never copies, stores, or redistributes any registry's component source. Every component you install still comes directly from its own registry via npx shadcn add <url>.

3,717 components total. The first six are the original motion/marketing family; the middle three are a product-UI expansion (forms, tables, dashboards, data display) added after checking each registry's demo/duplicate conventions individually rather than assuming they match the original six; cnippet and uiable are a second product-UI expansion, added the same way. Two other candidates from that same expansion are not indexed, see Limitations below. aceternity's count already excludes 163 page-template components a real per-item availability check found paywalled at their actual install URL; shadcn-dashboard's count already excludes 165 components for the same reason; shadcnblocks was tagged but is not currently indexed, see Limitations below. Tagging runs through classifier.dev, a free, keyless classification endpoint backed by TypeSafe's Jev decision model.

matchcn is an independent, unofficial project. It is not affiliated with, endorsed by, or a partner of shadcn, any of the registries above, or classifier.dev/TypeSafe.

Limitations

Read this before relying on matchcn for something important.

• Some registries are partly or fully excluded for paywalled components, found by a real per-item availability check (does npx shadcn add actually work unauthenticated, not just what the index claims): aceternity (163 of 282 tagged components, mostly page-template demo pages) and shadcn-dashboard (165 of 508) had the gated share filtered out before shipping. shadcnblocks was tagged (4,171 components) but is held back entirely: its own filter check got contaminated by the vendor's rate limiter, so it ships once a clean check runs rather than on bad data. shadcnuikit and shadcn-space were evaluated and skipped outright for the same reason (40% and 33.3% paywalled). cult-ui.com isn't indexed at all: its registry sits behind a bot challenge.
• Tag confidence varies by registry and dimension, and the matcher already accounts for it. visual_density is the weakest dimension overall. assistant-ui (agent/chat UI content, far from the schema's motion/marketing anchors) and uiable (largely name-echoed, auto-generated descriptions) tag less confidently than the rest of the catalog; cnippet and uiable haven't had a full-scale confidence measurement yet. A confidence-weighted matcher discounts all of this automatically, so a weak tag pulls its own weight down instead of producing a wrong confident answer, but a brief that leans heavily on these registries or on visual density is the one most likely to get a shortlist or no-match instead of a clean pick.
• Non-English briefs are known to be weaker. Tested directly: an English brief and its translated equivalent were compared side by side, and English found a real, well-tagged match that the translated version did not. Do not assume non-English input works as well.
• 11 of 372+ shadcn-format registries are indexed. This is not a comprehensive index of the ecosystem.

None of the above produces a wrong forced answer: when confidence is genuinely low, pick_component returns a shortlist or an explicit no-match, never a single silent guess. That is the actual point of the tagging and ranking design, not a disclaimer bolted on afterward.

Development

pnpm install
pnpm mcp          # run the MCP server directly, for local testing
pnpm demo         # run 3 briefs end to end with clean terminal output
pnpm typecheck

License

MIT, see LICENSE.