matchcn

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.

Related MCP server: OriginUI MCP Server

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>.

3,880 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. shadcn-dashboard's count already excludes 165 components a real per-item availability check found paywalled at their actual install URL; 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.

• shadcnblocks is not indexed, despite being tagged. A real per-item availability check (does npx shadcn add actually work unauthenticated, not just what the index claims) found roughly half of its components return 401/403 "License required" at their real install URL, something invisible in the registry's own index data. shadcn-dashboard had the same problem at a smaller scale (32.5%) and was fixed by filtering the paywalled components out before shipping; shadcnblocks' own full-scale check got contaminated by the vendor's rate limiter partway through before a clean filter could be produced, so it was pulled entirely rather than shipped unfiltered or filtered against bad data. Its tagged data is preserved, not lost, and it is expected back once a clean check runs.

• visual_density is the weakest tagged dimension. A confidence-weighted matcher discounts weak tags automatically, but a brief that hinges heavily on visual density is the most likely to disappoint.

• assistant-ui tags the least confidently of any indexed registry. Its content (agent and chat UI: tool timelines, reasoning panels) sits further from the schema's original motion/marketing anchors than anything else in the catalog, so assistant-ui-heavy briefs are more likely to return a shortlist or no-match than a confident pick.

• uiable's descriptions are mostly name-echoed templates ("Button component.") rather than hand-written text, so its tags carry less real signal than the rest of the catalog. Shipped as-is rather than blocked on; treat matches from this registry as less certain.

• cnippet and uiable have not yet had their tag confidence measured at full scale. A 20-item pre-tagging sample across both scored 35% under 0.6 confidence, higher than the rest of the catalog; treat these two as less proven until a full remeasurement runs.

• 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.

• aceternity's demo/block components are tagged from short index descriptions only, not enriched from full source, due to an access restriction on that registry's per-item endpoint.

• cult-ui.com is not indexed. Its registry sits behind a bot challenge that a standard request cannot pass.

• shadcnuikit and shadcn-space are not indexed. A real per-item availability check found genuine paywalls on 40% and 33.3% of a sample from each, not worth the added complexity.

• 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.

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.