Hash Generator
Hash text or a file locally in your browser. Nothing is uploaded, so you can safely check confidential documents.
| Algorithm | Digest |
|---|
File checksum
What a hash function does
A cryptographic hash turns any input, of any size, into a fixed-length fingerprint. The same input always produces the same digest; changing a single bit produces a completely different one; and there is no practical way to run the process backwards. That combination makes hashes useful for verifying integrity, deduplicating data and storing password verifiers.
Which algorithm to use
| Algorithm | Digest size | Status |
|---|---|---|
| MD5 | 128 bits | Broken. Collisions can be produced in seconds. Non-security checksums only. |
| SHA-1 | 160 bits | Broken. A practical collision was demonstrated in 2017; browsers and certificate authorities rejected it years ago. |
| SHA-256 | 256 bits | Recommended. The current default for signatures, certificates and file integrity. |
| SHA-384 / SHA-512 | 384 / 512 bits | Also fine, and often faster than SHA-256 on 64-bit hardware. |
| CRC32 | 32 bits | Not cryptographic at all — an error-detection checksum for archives and network frames. |
Never hash passwords with these
SHA-256 is designed to be fast, which is exactly wrong for passwords: a modern GPU computes billions of SHA-256 hashes per second. Password storage needs a deliberately slow, salted, memory-hard function — Argon2id, scrypt or bcrypt. Use a maintained library and never write your own scheme.
Verifying a download
Projects publish a SHA-256 digest next to their release files. After downloading, hash the file and compare. A mismatch means the file is corrupt or has been tampered with. Note that a checksum hosted on the same page as the download only protects against corruption — for tamper protection you need a signature from a key you already trust.
Collisions and preimages
A collision is two different inputs with the same digest; a preimage is finding an input that produces a given digest. Collision resistance is the weaker property and is what falls first — MD5 and SHA-1 are collision-broken but not preimage-broken, which is why old md5sum checks still catch accidental corruption even though they cannot stop a determined attacker.
Frequently asked questions
Is my file uploaded to compute the hash?
No. The Web Crypto API hashes the file in your browser. You can disconnect from the network and the tool still works.
Can a hash be reversed?
Not by computation. Short or common inputs can be found by brute force or in a rainbow table, which is why password hashing needs a unique salt and a deliberately slow algorithm.
Why is MD5 still everywhere if it is broken?
It is fast and short, and for detecting accidental corruption it works fine. The break matters when an attacker can choose the input — then two different files can be crafted with the same MD5.
Why does the same file give a different hash on another site?
Almost always a different algorithm, or a text input with different line endings. A file that ends \r\n on Windows hashes differently from the same file with Unix line endings.
What is the difference between hex and Base64 output?
Both encode the same bytes. Hex is twice the digest length and easy to read; Base64 is about a third shorter and is what HTTP headers such as Content-Digest and subresource integrity attributes use.