Fingerprint any file or photo in your browser, anchor it to Bitcoin and Ethereum, and prove possession in zero-knowledge. BoC gives you a tamper-evident record anyone can verify, with ownership transferable on-chain.
Blockchain of Custody® pairs in-browser hashing with direct anchoring on Bitcoin and Ethereum, a tamper-evident event log, and proofs anyone can check independently.
Files are fingerprinted with SHA-256 right in your browser. In hash-only mode the bytes never leave your device, yet the record stays provable.
Batched Merkle roots committed directly to Bitcoin and Ethereum, providing immutable timestamping secured by billions of dollars of PoW+PoS.
Each custody event is cryptographically chained to the last, making the full history append-only — any edit, deletion, or back-dating is immediately detectable.
A zero-knowledge proof that you currently hold the file behind a record's hash — bound to your wallet and a recent Bitcoin block, with the file kept private.
Export a self-contained proof bundle anyone can re-check against the public chains — no BoC account, no server, no trust required.
Hand custody to a verified wallet on-chain. Ownership is first-to-anchor plus transfer, recorded immutably and verifiable by anyone.
Upload a file or photograph a document. BoC computes the SHA-256 hash locally in your browser.
The fingerprint is batched into a Merkle root and committed to Bitcoin and Ethereum.
Export an offline-verifiable bundle, prove possession in zero-knowledge, or transfer custody on-chain.
Notarize your first piece of evidence in minutes — or verify an existing proof bundle without an account.