Hash / HMAC tool
Generate a hexadecimal digest or compare an existing digest using the selected algorithm.
A hash is not encryption
A cryptographic hash maps arbitrary input to a fixed-size digest. It is designed as a one-way transformation: there is no decryption key that recovers the original input from the digest.
Prefer modern algorithms for new integrity uses
SHA-256 and SHA-512 belong to SHA-2, while SHA3-256 and SHA3-512 belong to SHA-3. Both families are suitable modern choices for cryptographic hashing when the surrounding protocol and implementation are appropriate.
HMAC adds authentication with a shared secret
HMAC combines a cryptographic hash function with a secret key. It is used when integrity alone is not enough and the recipient also needs evidence that the message was produced by someone who knows the shared secret.
MD5 and SHA-1 remain only for compatibility
MD5 and SHA-1 are available here to reproduce or verify values encountered in legacy systems. They should not be selected for new applications that depend on collision resistance.
Raw hashes are not password storage functions
Passwords should be stored with a password hashing function designed to be deliberately expensive, such as Argon2id or bcrypt through PHP password_hash(). SHA-256, SHA-512 and SHA-3 are fast general-purpose hash functions and are not substitutes for a password hashing scheme.
One invisible character changes the result
Hashing operates on bytes. A trailing space, a newline, different character encoding or a capitalization change produces a different digest. When comparing values between systems, confirm exactly what data each side hashes.