Not just our feeds. Witness any API.

Route a third-party API call through Dynamic Feed and get back a signed record of exactly what that URL returned to us: the status, the content type, the size and the SHA-256 of the response body, timestamped and archived. Prove what a pricing API quoted, what a tracking API reported, what a ratings endpoint said, at the moment you relied on it. You are no longer limited to the sources we run: any data in flight can carry a receipt.

Build a call ↓API docs ↗

HOW IT WORKS

One call in, one receipt out.

STEP 01

Point

POST the URL (and any method, headers or body it needs) to /v1/proxy-witness. Your credentials reach the target but are redacted from the record and never stored.

STEP 02

Witness

We fetch it server-side under an SSRF guard, then sign a proxy-witness/v1 receipt of the response: status, content type, size and the SHA-256 of the body, at a timestamp.

STEP 03

Hold

Keep the receipt. Anyone can re-verify the signature against our published key. In a later dispute it shows exactly what the API returned to a neutral third party, then.

LIVE · BUILD A CALL

Witness a public API, copy-ready.

Enter any public https API URL. We build the exact call for you. Dynamic Feed fetches it server-side and returns the signed receipt. Only public http and https targets are witnessed: private and reserved addresses are blocked, and redirects are recorded rather than followed.

Step 2 · POST it (copy-ready)

Auth is a free self-serve key at POST /signup. The response comes back as the receipt below (this is a representative example of the shape you receive). Re-verify it any time at /verify against /.well-known/keys.

PROXY-WITNESS/V1 · EXAMPLEEd25519 signed

Request
GET https://api.github.com/zen

host api.github.com · credentials redacted, never stored

Response
200 · text/plain · 43 bytes
sha256:8b1a9953c4611296a827abf8c47804d7…

witnessed_at
2026-07-06T07:00:00Z · archived hash-first (the body is not stored unless you set echo:true)

The full receipt carries the Ed25519 signature and key_id and re-verifies at /verify. It attests what the URL returned to Dynamic Feed at that moment, not that the content is accurate.

WHERE IT HELPS

Every API becomes evidenceable.

A fintech proving what a market-data or FX API quoted at execution time. A logistics operator proving what a carrier's tracking API reported at handover. An insurer proving what a third-party ratings or hazard API returned when a policy was priced. An AI team proving what an upstream model or tool endpoint answered before it acted. In each case the fight is over what an outside service said at a moment, and neither party fully controls it. A signed record from a neutral witness, re-verifiable by both sides, turns that into something checkable instead of contestable.

Data with Receipts. The receipt proves this exact response was returned to us at that time and has not changed since. By default only the fingerprint is kept: set echo:true to include the body in your own receipt, and it still never enters our archive.

THE BOUNDARY

A witness in the middle, never in the way.

held on purpose

Dynamic Feed is a neutral witness. A proxy-witness receipt attests that we fetched this URL and received this exact response at a moment; it does not claim the response is accurate, and it does not authenticate who operates the API. We forward your request to reach the target but redact your credentials from the record, and we archive hash-first so response contents are not retained by default. Only public targets are witnessed; private and reserved addresses are blocked. We are never in the money path and we never make the call for you. Advisory evidence, tamper-evident not tamper-proof, not a certification and not legal advice.

FOR FINTECH, LOGISTICS, INSURANCE & AGENT BUILDERS

Wrap any call. Keep the receipt.

One endpoint witnesses any third-party API, hash-first and self-serve. Your coverage is no longer limited to the feeds we run.

The notary ↗Receipt spec ↗