Hash Generator
Generate MD5, SHA-1, and SHA-256 cryptographic hashes from any text string instantly in your browser. No data is sent to a server.
— — — Frequently Asked Questions
What is a hash function?
A hash function is a deterministic algorithm that transforms an arbitrary-length input into a fixed-length output called a digest or hash. The same input always produces the same hash, but even a tiny change in the input — such as flipping a single bit — produces a completely different hash. This property, known as the avalanche effect, makes hash functions useful for verifying data integrity: if you hash a file before and after transfer and the hashes match, the file arrived unchanged.
MD5 vs SHA-1 vs SHA-256 — which should I use?
MD5 produces a 128-bit (32-character hex) digest and is very fast, but it is cryptographically broken — collision attacks exist that can generate two different inputs with the same MD5 hash. It should not be used for security purposes but is still acceptable for non-security checksums and fingerprinting. SHA-1 produces a 160-bit (40-character hex) digest; it is also considered weak for security-critical applications since 2017 when Google demonstrated a practical collision. SHA-256 is part of the SHA-2 family, produces a 256-bit (64-character hex) digest, and remains secure and widely recommended for passwords (combined with a salt), digital signatures, and data integrity verification.
Are these hashes reversible?
No. MD5, SHA-1, and SHA-256 are all one-way functions: given a hash, there is no mathematical algorithm that can reconstruct the original input. This irreversibility is a fundamental design property. What attackers can do instead is try rainbow table attacks (precomputed tables of hash→input pairs) or brute-force all possible inputs and compare. This is why passwords should always be hashed with a slow, salted algorithm like bcrypt, scrypt, or Argon2 rather than fast general-purpose hashes like SHA-256.