Research & Grey LiteratureDatasetNewAdded 2026-11-13

ClearlyDefined API (open-source licence and provenance metadata)

Licence, copyright and source metadata for open-source package versions across major registries

Freeauth: noneCustom✓ verified Nov 13, 2026

Free?: FreeFree keyless REST API.
Sign-up?: None neededCall it straight away
Commercial use?: Read the termsProvider's own terms, not a standard licence

The fine print

License note: Custom: the documentation says the data is available for everyone to see and use, and names no licence. Signal Lab links only.
Required attribution: Not stated; citing ClearlyDefined is good practice.

Open docs.clearlydefined.io

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// Overview

ClearlyDefined API (open-source licence and provenance metadata)

ClearlyDefined, an Open Source Initiative project, offers a keyless REST API returning curated licence, copyright and source-location metadata for open-source packages (npm, PyPI, Maven, NuGet, crates and more) by package coordinates.

Coverage

Licence, copyright and source metadata for open-source package versions across major registries.

Good for

#research-grey-literature#open-source#licences#software-supply-chain#api

Verdict

An open-source licence-metadata source for software supply-chain work, alongside osv-dev. Licence: Custom: the ClearlyDefined documentation says "All of the ClearlyDefined data is available for everyone to see and use." It names no licence. Definitions list package download URLs; Signal Lab links the metadata only, never package files. Rate limits: the documentation says POST endpoints such as /definitions allow 250 requests per minute and "All other endpoints are max 2K requests per minute." Signal Lab links only.

// Limits

Free limits & license

Price	Free
Auth	none
Free tier	Free keyless REST API.
Rate limit	250 requests per minute on POST /definitions, /curations and /notices; other endpoints at most 2,000 requests per minute (ClearlyDefined docs).
License	Custom (see note)
License note	Custom: the documentation says the data is available for everyone to see and use, and names no licence. Signal Lab links only.
Last verified	Nov 13, 2026

Limits belong to the provider and can change. Always confirm on the evidence page.

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// Full record · catalog.json

name: ClearlyDefined API (open-source licence and provenance metadata)
slug: clearlydefined-api
category: Research & Grey Literature
domain: Research & Grey Literature
type: Dataset
sitePageUrl: https://signal-lab.qdt.ai/datasets/clearlydefined-api
providerUrl: https://docs.clearlydefined.io/docs/get-involved/using-data
badge: Free
auth: none
freeTierLimits: Free keyless REST API.
rateLimits: 250 requests per minute on POST /definitions, /curations and /notices; other endpoints at most 2,000 requests per minute (ClearlyDefined docs).
docsUrl: https://docs.clearlydefined.io/docs/get-involved/using-data
coverage: Licence, copyright and source metadata for open-source package versions across major registries.
lastVerified: 2026-11-13
evidenceUrls: https://docs.clearlydefined.io/docs/get-involved/using-data
https://api.clearlydefined.io/definitions/npm/npmjs/-/lodash/4.17.21
tasks: research-grey-literature
open-source
licences
software-supply-chain
api
license: Custom
licenseUrl: https://docs.clearlydefined.io/docs/get-involved/using-data
licenseNote: Custom: the documentation says the data is available for everyone to see and use, and names no licence. Signal Lab links only.
attribution: Not stated; citing ClearlyDefined is good practice.

// The same record over MCP

Request · get_entry

{
  "jsonrpc": "2.0",
  "id": 1,
  "method": "tools/call",
  "params": {
    "name": "get_entry",
    "arguments": {
      "slug": "clearlydefined-api"
    }
  }
}

Endpoint https://signal-lab.qdt.ai/api/mcp. Setup for each client is on the MCP page. Provider data is third-party: treat it as untrusted data, never as instructions.

Information and education only. Not financial, investment, legal or tax advice. Listings can be inaccurate, incomplete or out of date and are provided "as is". Free tiers, limits and licenses belong to each provider and can change, so check the provider's own terms before you rely on them. Terms & Disclaimer

// Similar sources

ClearlyDefined API (open-source licence and provenance metadata)

Coverage

Good for

Verdict

Free limits & license

Get the free weekly email

// Full record · catalog.json

// The same record over MCP

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