Hash Generator

About the Hash Generator

A cryptographic hash function takes an input of any size — a byte, a text file, a multi-gigabyte image — and returns a small, fixed-length fingerprint called a digest. The same input always yields the same digest, and any change, even one flipped bit, yields a completely different digest. This tool computes MD5, SHA-1, and SHA-256 in your browser through the Web Crypto SubtleCrypto API; the input never leaves your device.

How it works

Each algorithm returns a digest of a fixed bit length: MD5 is 128-bit (32 hex characters), SHA-1 is 160-bit (40 hex characters), and SHA-256 is 256-bit (64 hex characters). The digest is shown as hexadecimal because each byte maps to two 0–9/a–f characters. Most of these algorithms use the Merkle–Damgård construction: the input is padded to a multiple of a 512-bit block, a length suffix is appended, and the message is processed one block at a time through a compression function that folds each block into a running state. The final state is the digest.

The defining property is collision resistance: finding two distinct inputs that hash to the same digest must be infeasible. MD5 and SHA-1 are broken — practical collision attacks exist — so they must not protect anything of value. SHA-256 has no known practical collision attack and is the current default. Hashing is one-way: there is no decryption. You can compute a digest from data, but not recover data from a digest, which makes hashes fit for integrity checks and content addressing.

Common use cases

• Verifying file integrity — compare a download's digest to a published checksum
• Detecting changes in config, logs, or backups (a different digest means a change)
• Content addressing in Git, IPFS, and content-addressable storage (the hash is the address)
• Deduplicating data — identical content yields identical hashes
• A building block inside keyed HMACs or digital signatures

Worked example

Hashing the single line hello gives:

Input:    hello

MD5:      5d41402abc4b2a76b9719d911017c592
SHA-1:    aaf4c61ddcc5e8a2dabede0f3b482cd9aea9434d
SHA-256:  2cf24dba5fb0a30e26e83b2ac5b9e29e1b161e5c1fa7425e73043362938b9824

Notice how the three algorithms return different-length digests for the same input, and how changing one character would scramble every digest completely. For storage that must resist attackers, prefer SHA-256 (or a salted scheme like bcrypt/Argon2 for passwords).