eXist-db (or eXist for short) is an open source software project for NoSQL databases built on XML technology. It is classified as both a NoSQL document-oriented database system and a native XML databa
1. Compute SHA-256 of OTSCanonicalRecord value → must equal OTSHash 2. Open OTSProofURL → extract Bitcoin block number → must equal OTSBitcoinBlock 3. GET OTSBitcoinBlockVerifyURL → returns the Bitcoin block hash at height OTSBitcoinBlock; GET https://blockstream.info/api/block/{that hash} → its timestamp must match OTSTimestamp 4. Read CopyrightID inside OTSCanonicalRecord → must equal the CopyrightID above 5. GET OTSVerificationAPI → pre-computed 6-check result from server 6. If all match: this entity was registered on CopyrightChains at OTSTimestamp, independently verifiable on Bitcoin Note: an OTS proof may carry multiple Bitcoin attestations; OTSBitcoinBlock is the earliest confirmed one — a later attestation inside the proof corroborates it and is not a mismatch
Dual-chain trust anchor. Chain 1 (CopyrightChains): CopyrightID 0x7cfb9ea869b19e419b8ef7c8fa22a9fc5492ca0c92ef094c6a4d9df6b938dfc8. Chain 2 (Bitcoin): anchored in block 954516 (2026-06-20T07:04:44Z). Bridge: the canonical record inside this Bitcoin proof contains the same CopyrightID. Verify: download https://artists.proofprofile.net/proofs/artist/a292a841-eb96-4854-9d66-4fa5f69c9e3e.json and https://artists.proofprofile.net/proofs/artist/a292a841-eb96-4854-9d66-4fa5f69c9e3e.ots, run `ots verify -f record.json proof.ots` (https://opentimestamps.org).