Hash chain
A sequence of cryptographic hashes where each entry commits to all history before it.
A hash function turns any data into a short fingerprint. Change one digit of the data and the fingerprint changes completely. A hash chain links daily fingerprints together: each day's hash is computed from that day's data plus the previous day's hash.
The consequence is tamper-evidence. Editing any historical entry changes its hash, which changes the next day's hash, and so on to the end of the chain. Anyone holding the published chain can recompute it and detect the edit. This is the same principle blockchains use, without needing a blockchain.
This platform seals every strategy's daily snapshot into such a chain and publishes the file itself. The verify page recomputes it in your browser on demand.