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TRUST CENTER · THE FONTEUM TRUST MARK

Every fact carries a signed, re-checkable mark.

A fact is not just a string. It is a string plus who attested it, as of when, signed by whom, and where to independently re-check it. Fonteum attaches that envelope to every fact it serves — so any consumer, whether a human, an app, or an AI crawler, carries “signed by Fonteum, re-checkable” with the data instead of an anonymous, un-attributable value. This is the “Powered by Plaid” of facts.

The attribution rides along — on every surface

The same trust mark is attached additively wherever Fonteum serves data, without changing any existing response shape:

  • REST API — an attestation block on every /api/v1 response's meta, plus X-Fonteum-Trust-Mark + X-Fonteum-Recheck headers.
  • MCP — an attestation sibling on every tool result, so an AI agent grounding over MCP carries the mark with the fact.
  • FHIR R4 — _attested_by + _recheck_urlcodings on every resource's meta.tag, beside the live signature-chain head.
  • Crawled pages — a visible, server-rendered byline in the site footer so GPTBot / ClaudeBot ingest the branded, re-checkable mark rather than anonymous data.
"attestation": {
  "attested_by": "Fonteum",
  "standard": "W3C-VC-2.0",
  "content_credential": "C2PA-aligned Content Credentials for facts",
  "source": "CMS NPPES NPI Registry",
  "as_of": "2026-05-01",
  "attestation_id": 1042,
  "signature": "9f2c…<ed25519 chain-head hash>",
  "recheck_url": "https://fonteum.com/verify/1042",
  "key_url": "https://fonteum.com/.well-known/chain-public-key.json",
  "docs_url": "https://fonteum.com/trust/trust-mark"
}

Built on open standards

The signed attestation is expressed in a W3C Verifiable Credentials 2.0-compatible form with a DataIntegrityProof using the EdDSA cryptosuite (eddsa-jcs-2022) — the same Ed25519 key that signs Fonteum's append-only attestation chain. We frame this as Content Credentials for facts: a tamper-evident, portable credential aligned with C2PA's content-provenance model, but for a data fact rather than a media asset. We ride the winning standards rather than invent a wire format others must learn.

Fetch the credential for any attested snapshot at https://fonteum.com/verify/<id>?format=vc (or with Accept: application/vc+json). The public key backing every signature is published at /.well-known/chain-public-key.json.

{
  "@context": [
    "https://www.w3.org/ns/credentials/v2",
    "https://fonteum.com/ns/trust-mark/v1"
  ],
  "type": ["VerifiableCredential", "FonteumFactCredential"],
  "issuer": { "id": "https://fonteum.com", "name": "Fonteum" },
  "validFrom": "2026-05-01T00:00:00Z",
  "credentialSubject": {
    "id": "https://fonteum.com/verify/1042",
    "source": "CMS NPPES NPI Registry",
    "asOf": "2026-05-01",
    "recheckUrl": "https://fonteum.com/verify/1042"
  },
  "proof": {
    "type": "DataIntegrityProof",
    "cryptosuite": "eddsa-jcs-2022",
    "verificationMethod": "https://fonteum.com/.well-known/chain-public-key.json",
    "proofPurpose": "assertionMethod",
    "proofValue": "<base64url Ed25519 signature>"
  }
}

Re-check it yourself

The mark points at a real, public destination. Hand any attestation id to https://fonteum.com/verify/<id> and you get back the source, the as-of date, the published content hash, the Ed25519 signature, and confirmation it matches the primary record — no Fonteum account, no private key required. Anyone, or any AI, can independently re-check a Fonteum fact.

Related

  • · /verify — re-check any snapshot
  • · /chain — the append-only attestation chain
  • · /trust/data-provenance — per-source license + redistribution
  • · /methodology — per-field provenance contract
  • · /trust — Trust Center hub

Built on the authoritative federal record

The primary sources, named on every page.

These are the federal agencies whose public datasets Fonteum ingests and attributes — the issuing authorities, not customers or partners. Every figure on the site links back to one of them.

  • CMS
  • HHS-OIG
  • HRSA
  • FDA
  • NLM
  • NUCC
  • Census
  • BLS
  • BEA

See the full source registry, with license and refresh cadence for each →

Reproducible by design

Every figure traces to its federal source.

14-tuple provenance

Every rendered fact ties to a source URL, dataset ID, snapshot date, row key, and SHA-256 — the full chain-of-custody record.

Reproducible SQL

Each study ships the exact query behind its figures, run against the cited federal snapshot. Re-run it yourself.

Daily reconciliation

Published counts are reconciled against the upstream federal datasets on a daily cadence, with drift logged.

Named medical review

Reviewed by Jennifer Montecillo, MD, medical reviewer. Non-practicing medical reviewer.

Read the full provenance and attestation methodology →

Two doors

Use the free API and open data

Query providers, facilities, sanctions, and quality scores — each field carrying its federal source. Self-serve, no call to start.

Explore the API →Browse the data catalog →

Talk to us

Managed pilots, enterprise terms, and audit-ready, signed attestation packages for compliance, risk, and research teams.

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Reviewed by Jennifer Montecillo, MD, medical reviewer. Non-practicing medical reviewer.

© 2026 Fonteum LLC. All rights reserved.

·hello@fonteum.com

The U.S. healthcare graph AI can cite — every fact carries its source.

Every fact Fonteum serves carries a signed, re-checkable trust mark — source, as-of date, and an Ed25519 signature travel with the data. Re-check any fact at fonteum.com/verify · the trust-mark standard (W3C Verifiable Credentials 2.0, C2PA-aligned).
Request access→

The substrate, by the numbers

9.2Mgraph entitiesProviders, organizations, owners, and facilities
15.7Mlinked identifiersNPIs, CCNs, LEIs and more, resolved to entities
5Mgraph edgesSource-attested relationships between entities
44federal source familiesDistinct CMS, OIG, HRSA, FDA and peer datasets
35dataset pagesCitable, downloadable /data catalog pages
67reproducible studiesEach shipping the SQL behind its figures