linkedclaims.com / claim-lexicon
A minimal ATProto lexicon for verifiable claims, implementing the LinkedClaims specification.
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lexicons
appview-indexing-guide.md
HOSTING.md
proposal.md
README.md
specification-draft.md
README.md

Claim Lexicon #

A minimal ATProto lexicon for verifiable claims, implementing the LinkedClaims specification.

Documents #

  1. proposal.md - Initial proposal and rationale
  2. specification-draft.md - Technical specification
  3. appview-indexing-guide.md - Implementation guide for AppViews
  4. HOSTING.md - How to host and use this lexicon

Lexicon Files #

The actual lexicon JSON is in:

Quick Start #

import { Lexicons } from '@atproto/lexicon'
import { AtpAgent } from '@atproto/api'

// Load lexicon
const claimLexicon = require('./lexicons/community/claim.json')
const lexicons = new Lexicons([claimLexicon])

// Create a claim
const claim = {
  subject: 'https://example.org/project',
  claimType: 'impact',
  statement: 'Delivered 500 water filters',
  source: { howKnown: 'FIRST_HAND' },
  createdAt: new Date().toISOString()
}

// Validate
lexicons.assertValidRecord('community.claim', claim)

// Publish to ATProto
const agent = new AtpAgent({ service: 'https://bsky.social' })
await agent.login({ identifier: 'handle', password: 'app-password' })
await agent.com.atproto.repo.createRecord({
  repo: agent.session.did,
  collection: 'community.claim',
  record: claim
})

Key Design Decisions #

Claims are Immutable #

No versioning (prevCid removed). To update or correct a claim, create a new claim that references the original.

Attestations are Just Claims #

No special sigs field. An endorsement or dispute is a claim where the subject is another claim's AT-URI.

External Signatures Supported #

The embeddedProof field allows claims signed by MetaMask, aca-py, or other tools to be published on ATProto while preserving the original signer identity.

Example Claims #

Skill claim:

{
  "subject": "did:plc:alice",
  "claimType": "skill",
  "object": "React",
  "statement": "3 years production experience",
  "createdAt": "2025-02-14T18:22:00Z"
}

Endorsement of another claim:

{
  "subject": "at://did:plc:alice/community.claim/3kfxyz",
  "claimType": "endorsement",
  "statement": "I can confirm this is accurate",
  "source": { "howKnown": "FIRST_HAND" },
  "createdAt": "2025-02-15T10:00:00Z"
}

Claim with external signature:

{
  "subject": "did:plc:bob",
  "claimType": "endorsement",
  "statement": "Trustworthy collaborator",
  "createdAt": "2025-02-14T18:30:00Z",
  "embeddedProof": {
    "type": "EthereumEip712Signature2021",
    "verificationMethod": "did:pkh:eip155:1:0x1234...",
    "proofValue": "0xabc123...",
    "proofPurpose": "assertionMethod",
    "created": "2025-02-14T18:30:00Z"
  }
}

License #

MIT