witnessd
A neutral witness for the machine-readable web.
An agent can compute anything but can witness nothing about itself — and neither can the counterparty it's about to argue with. witnessd is a third party: pay a few cents and it independently fetches any URL or API endpoint right now, hashes and timestamps the response, archives it, and hands you a signed certificate. Snapshot hashes are Merkle-batched every hour and anchored in a transaction on Base, so the record is verifiable by anyone, forever — including people who don't trust us.
Witness a counterparty's published price before you transact. Witness the API response you were served before you act on it. When there's a dispute, the evidence already exists.
Pricing
| Endpoint | Price | What you get |
|---|---|---|
POST /api/witness | $0.02 | Independent fetch + signed certificate + archival |
GET /api/certificate/:id | free | Certificate + Merkle proof + anchor tx (after hourly batch) |
GET /api/retrieve/:id | $0.05 | The archived body + certificate — any snapshot, any payer |
POST /api/credits | $1.00 | Prepaid API key (100¢) — needed for scheduled watches |
POST /api/watch | 2¢ / fetch, prepaid | Scheduled witnessing of an endpoint (≥10 min interval) |
Machines pay per-call with USDC via x402 — no account, no key, no human. Humans can buy prepaid credits with a card (Stripe link) or just use x402 too.
For agents
# x402 (no account needed — your wallet pays the 402 challenge)
curl -X POST https://DOMAIN/api/witness -H 'content-type: application/json' \
-d '{"url":"https://api.example.com/v1/price"}'
# MCP: mount the witness as a tool
npx witnessd-mcp # env: WITNESSD_URL, then EVM_PRIVATE_KEY or WITNESSD_API_KEY
Machine-readable: llms.txt · openapi.yaml
Don't trust us — check
Certificates verify offline: recompute sha256(canonical-json(manifest)), check the Ed25519
signature, fold the Merkle proof to the batch root, and compare that root with the calldata of the anchor
transaction on Base (0x + wtns1 + root). A tampered archive is mathematically visible.
Standalone verifier: verify.js.
What this is not
witnessd provides cryptographic evidence, not legal conclusions; it is not an eIDAS qualified timestamp service and nothing here is legal advice. Archived content is served privately to paying requesters as evidence and is never republished. Scheduled watches respect robots.txt. We cannot witness content behind your own login — by design; a neutral witness sees what any stranger sees. Terms.