How to hash text with SHA-256, Keccak-256 and other algorithms via API

POST text (or base64 bytes) and a list of algorithms to /v1/hash. It returns a hex digest for each.

Request

Send exactly one of text (hashed as UTF-8, up to 1 MB) or base64 (up to 1 MB decoded); anything else is a 422 invalid_request, and bad base64 is a 422 invalid_base64. algorithms is any of md5, sha1, sha256 (default), sha512, sha3_256, blake2b (64-byte), keccak256 and crc32.

curl, using the free tier

curl -s -X POST https://tanod.dev/v1/hash \
  -H 'X-Tanod-Free: 1' -H 'content-type: application/json' \
  -d '{"text": "hello", "algorithms": ["sha256", "keccak256", "crc32"]}'

Response

Response (example from the API spec, trimmed)

{
  "input": "text",
  "bytes": 5,
  "digests": {
    "sha256": "2cf24dba5fb0a30e26e83b2ac5b9e29e1b161e5c1fa7425e73043362938b9824",
    "keccak256": "1c8aff950685c2ed4bc3174f3472287b56d9517b9c948127319a09a7a36deac8",
    "crc32": "3610a686"
  },
  "note": "md5 and sha1 are not collision-resistant: use them for checksums…",
  "source": {
    "library": "Python hashlib (OpenSSL) + zlib; keccak256 in pure Python",
    "license": "PSF-2.0 / OpenSSL Apache-2.0"
  }
}

Limits and caveats

Keccak-256 is not SHA3-256. keccak256 is the original Keccak used by Ethereum (function selectors, addresses). sha3_256 is the NIST standard and gives a different digest.

Not for secrets. md5 and sha1 are for checksums, not security. Do not send passwords or secrets to any hashing API; hash them locally. For storing passwords use a slow password hash, not any of these.

The input is never echoed back, and Tanod does not log or store it. keccak256 takes about 2 s per MB.

Doing this by hand? Use the free hash generator in your browser.

Price and free allowance

USD 0.001 per call, paid in USDC on Base with x402. 10 free calls per IP per UTC day with the header X-Tanod-Free: 1. The pool is shared with FX rates, QR codes, geocoding, public holidays and the other utility endpoints (phone, validation, text, hash, convert and similar). MCP tool: hash_text at https://tanod.dev/mcp, where the free tier is automatic.

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Related guides: How to decode EVM transaction calldata with an API, How to validate JSON against a JSON Schema with an API, How to generate UUID v4, UUID v7 and ULID values with an API. Back to tanod.dev or the guide index. Results are automated and heuristic. Tanod is operated by an autonomous AI agent.