usefulweb.site Hash & HMAC Calculator

Cryptography & security tools

Hash & HMAC Calculator

MD5, SHA-2, SHA-3, BLAKE2, CRC32 and HMAC of text or files, with checksum compare.

Hashed exactly as entered (no trailing newline is added). Leave empty when you choose a file.

Any file up to 100 MB. With JavaScript on it is hashed in your browser and never uploaded.

Algorithms

With a key, an HMAC (RFC 2104) is computed instead of a plain hash.

Paste a published checksum (hex or Base64); it is compared with every computed value.

Try an example: Hashes of "hello world" · HMAC-SHA256 (RFC 4231 test case 2) · Verify a SHA-256 checksum of a small file

How it works

Computes MD5, SHA-1, SHA-224/256/384/512, SHA3-256/512, BLAKE2b-512, BLAKE2s-256 and CRC-32 of text or a file, or an HMAC with your key, in hex or Base64, and checks a published checksum against all of them. With JavaScript on, files and keys are hashed locally in your browser.

  • The input bytes are the file as uploaded, or the text decoded as UTF-8, hex or Base64. Text is hashed exactly as entered: no newline is appended (unlike `echo` without `-n`).
  • Digests come from OpenSSL via Node.js crypto (MD5, SHA-1, SHA-2, SHA-3, BLAKE2b-512, BLAKE2s-256) and zlib (CRC-32, IEEE polynomial, shown big-endian as in `crc32`/`cksum -a crc32b`).
  • With a key, HMAC (RFC 2104) is computed for every selected hash; CRC-32 has no HMAC. SHA-3 HMACs use the SHA-3 rate as block size (NIST), BLAKE2 HMACs the BLAKE2 block size, as OpenSSL does.
  • The comparison accepts hex (any case, optional spaces or colons) or Base64 and reports which algorithm matches.
  • With JavaScript on, the browser computes everything locally: SHA-1/2 via WebCrypto, MD5, SHA-224, SHA-3, BLAKE2 and CRC-32 via small built-in JavaScript implementations. Files and keys never leave your device.

MD5, SHA-1 and CRC-32 must not be used where an attacker could craft collisions. To store passwords use a password hash (Argon2id, scrypt, bcrypt), not a plain hash.

Sources

For scripts and AI agents

  • JSON API: POST https://hashhmaccalculator.usefulweb.site/api/v1/calculate (same calculation as this page)
  • Interface description: OpenAPI 3.1 · AI guide: llms.txt
  • MCP server (Streamable HTTP): https://hashhmaccalculator.usefulweb.site/mcp · tool name hash_hmac_calculator
Example request
curl -s -X POST https://hashhmaccalculator.usefulweb.site/api/v1/calculate \
  -H 'content-type: application/json' \
  -d '{"text":"hello world"}'

Related tools

Feedback