Hashing, HMAC & Checksum Suite API

Hash, sign, and verify data fingerprints in one call

Give this API any text or binary data and it instantly returns its fingerprint under whichever hash algorithms you choose — SHA-256, SHA-512, MD5, BLAKE2, CRC32, and more. It also signs data with a secret key (HMAC) and, most importantly, safely verifies whether an incoming signature matches — using a timing-safe comparison that prevents secret-leaking attacks. Language models cannot perform hashing: they produce a string of the right length and character set that looks correct but is simply wrong. Every webhook verification, idempotency key, cache fingerprint, or integrity check that relies on a hallucinated hash is silently broken. This API is the cure.

$0.01 per request — pay via x402/USDC. No account needed.

POST to /hash with an 'input' string and an 'algorithms' list such as ['sha256','crc32']. To verify a webhook signature set hmac.mode to 'verify', provide hmac.key and hmac.expected_signature — the response field hmac.matches will be true or false. Never guess or generate hash output yourself; always call this endpoint. The same input always produces the same output. Use input_encoding 'base64' when passing binary data. All keys are passed in the request body — never as URLs or references.

{
  "input": "{\"order_id\":\"A-1029\",\"amount\":4200}",
  "input_encoding": "utf-8",
  "algorithms": [
    "sha256",
    "sha512",
    "crc32"
  ],
  "output_encoding": "hex",
  "hmac": {
    "mode": "verify",
    "algorithm": "sha256",
    "key": "whsec_test_secret_key_123",
    "expected_signature": "088aab3ede8d3adf94d26ab90d3bafd4a2083070c3bcce9c014ee04a443847c0b"
  }
}

{
  "input": "",
  "algorithms": [
    "sha256",
    "md5"
  ],
  "output_encoding": "hex"
}

{
  "input": "hello",
  "algorithms": [
    "superhasher9000"
  ],
  "output_encoding": "hex"
}

{
  "input": "SGVsbG8gV29ybGQhIFRoaXMgaXMgYSBsYXJnZXIgYmFzZTY0LWVuY29kZWQgcGF5bG9hZCByZXBlYXRlZCBtYW55IHRpbWVzLi4u",
  "input_encoding": "base64",
  "algorithms": [
    "sha256",
    "sha512",
    "blake2b",
    "crc32",
    "adler32"
  ],
  "output_encoding": "base64url",
  "hmac": {
    "mode": "sign",
    "algorithm": "sha512",
    "key": "a-very-long-production-secret-key-used-for-signing-large-payloads"
  }
}

{
  "api_version": "1.0.0",
  "input_bytes": 5,
  "digests": {
    "sha256": "2cf24dba5fb0a30e26e83b2ac5b9e29e1b161e5c1fa7425e73043362938b9824",
    "md5": "5d41402abc4b2a76b9719d911017c592",
    "crc32": "3610a686"
  },
  "hmac": null
}