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.
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.
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.
Talk to us
Managed pilots, enterprise terms, and audit-ready, signed attestation packages for compliance, risk, and research teams.
The substrate, by the numbers
Each Fonteum snapshot is SHA-256 digested, Ed25519 signed, and hash-chained to the one before it — a Certificate-Transparency-style log where any change to a published fact is detectable by a single recomputation.
e46364aee887a1c9da3ef9f5440500dd054b0717d3e69de244b190f093b35d93Every dataset refresh produces a complete snapshot, SHA-256 digested at write time so its content is fixed to a single fingerprint.
The digest is signed with Fonteum's Ed25519 key. The matching public key is published, so anyone can confirm the signature offline.
Each digest references the prior snapshot's hash, forming an append-only, tamper-evident chain — alter one row and every later hash stops matching.
Diff two snapshots of a dataset and get every changed field with its full 14-tuple provenance attached. Try it now with the public pk_dx_sample key:
curl -s https://fonteum.com/api/v1/snapshots/diff \
-H "Authorization: Bearer pk_dx_sample" \
-H "Content-Type: application/json" \
-d '{
"dataset": "nppes",
"from_snapshot": "2026-04-01T00:00:00Z",
"to_snapshot": "2026-05-01T00:00:00Z",
"fields": ["taxonomy", "addresses"]
}'Response shape
{
"dataset": "nppes",
"from_snapshot": { "digest": "…", "signature": "…", "signing_key_fingerprint": "…" },
"to_snapshot": { "digest": "…", "signature": "…", "signing_key_fingerprint": "…" },
"changes": [
{
"npi": "1234567890",
"field": "taxonomy",
"change_type": "modified",
"before": { "value": "…", "provenance": { /* 14-tuple */ } },
"after": { "value": "…", "provenance": { /* 14-tuple */ } }
}
],
"summary": { "total_changes": 2, "added": 0, "removed": 0, "modified": 2 }
}Full reference: /docs/api/snapshots-diff
5ea9547e26ebaf18425098106658d4f979c6380c90ea7d0ea9f11bf917e71c87Call the snapshot diff API with pk_dx_sample, or drop our MCP server into your agent. No signup. No credit card. Live demo key.