A hash function takes input data of any size and produces a fixed-size output called a hash or digest. Hash functions are deterministic (same input always produces same output), fast to compute, and designed so that small changes in input produce completely different outputs. They are used in checksums, password storage, digital signatures, and data integrity verification.

MD5 produces a 128-bit (32 hex character) hash and is very fast, but is cryptographically broken — it is vulnerable to collision attacks and should not be used for security purposes. SHA-256 produces a 256-bit (64 hex character) hash and is cryptographically secure. Use SHA-256 for any security-sensitive application. MD5 is still useful for checksums where collision resistance is not required.

No. Hash functions are one-way functions — given a hash output, it is computationally infeasible to reconstruct the original input. This property is called pre-image resistance. While dictionary attacks and rainbow tables can sometimes reverse weak passwords, a properly generated hash of sufficient-length random input cannot be reversed.

Click "Hash a file" or drag and drop any file onto the input area. The tool reads the file using the FileReader API in your browser and computes MD5, SHA-1, SHA-256, and SHA-512 hashes simultaneously. The file is never uploaded — all hashing happens locally. This is useful for verifying file integrity by comparing hashes.

Yes. SHA-256 is part of the SHA-2 family and remains cryptographically secure as of 2026. It is widely used in TLS/SSL certificates, Bitcoin, and many security protocols. For password hashing specifically, use a dedicated password hashing function like bcrypt, scrypt, or Argon2 instead, as they are designed to be slow and resist brute-force attacks.