Applications

Where hashes show up

Interactive demonstrations of how real systems combine hash primitives. Pure understanding-builders, not production tools.

Bitcoin
Block hash (SHA-256d) and P2PKH address derivation (SHA-256 + RIPEMD-160 + Base58Check).
Git
Object IDs as SHA-1("blob <size>\0<content>"), and the same with SHA-256 for new repos.
JWT
HS256 = HMAC-SHA-256 over base64url(header).base64url(payload). The math behind the token in your browser console.
IPFS CIDs
Content addressing via multihash: SHA-256 → CIDv0 (Qm…) or CIDv1 (bafk…).
Subresource Integrity
Pin a hash of a remote script in your HTML. The browser hashes, verifies, refuses on mismatch.
TOTP
Six-digit codes from HMAC-SHA-1(secret, ⌊time/30⌋). The math behind every authenticator app.