Hash generator
Generate MD5, SHA-1, SHA-256, SHA-384 and SHA-512 hashes from text or any file, computed entirely on your device.
-----Ready · runs on your device
Nothing is uploaded. This tool runs entirely inside your browser tab. Your files and figures stay on your device - we never receive them, so we cannot read, store or lose them.
What a hash function does
A cryptographic hash maps input of any length to a fixed-length output, with three properties that make it useful:
- Deterministic - the same input always gives the same digest.
- One-way - recovering the input from the digest is computationally infeasible.
- Avalanche - changing one bit of input changes roughly half the output bits.
That third property is what makes hashes useful for integrity checking. A single altered byte anywhere in a 4 GB file produces a completely different digest:
"hello" → 5d41402abc4b2a76b9719d911017c592
"hellp" → 84b52b8afc1e35b2a7d99b5a6f8b1eb1The algorithms
| Algorithm | Output | Status |
|---|---|---|
| MD5 | 128 bits, 32 hex chars | Broken. Checksums only |
| SHA-1 | 160 bits, 40 hex chars | Broken. Being removed everywhere |
| SHA-256 | 256 bits, 64 hex chars | Secure. The current default |
| SHA-384 | 384 bits, 96 hex chars | Secure |
| SHA-512 | 512 bits, 128 hex chars | Secure. Faster than SHA-256 on 64-bit CPUs |
SHA-256, SHA-384 and SHA-512 are computed here with the Web Crypto API - the browser’s own native, audited implementation. Web Crypto deliberately omits MD5 to discourage its use, so that one algorithm alone comes from a small library.
Verifying a download
The most common legitimate use. A project publishes the SHA-256 of its installer; you compute it locally and compare.
- Download the file.
- Drop it into the File tab above.
- Compare the SHA-256 against the published value.
This detects corruption during transfer, and detects tampering only if you obtained the published hash through a channel the attacker does not control. A checksum listed on the same compromised page as the download proves nothing. Signed release manifests exist for this reason.
Comparing by eye, check the first and last six characters and the length. Anything engineered to fool you will match a prefix.
Why “broken” still ships
MD5 and SHA-1 remain widespread in Git object addressing, older package managers and file deduplication. That is not always negligence: collision attacks require an adversary who can choose both inputs. Against accidental corruption - a bad disk, a truncated download - MD5 is still perfectly effective.
The line is whether an adversary is in the picture. Detecting a corrupted download: fine. Signing anything, verifying identity, or storing credentials: never.
Hashing passwords
Password storage needs the opposite of a fast hash. Argon2id is the current recommendation, with scrypt and bcrypt as established alternatives. Each is deliberately expensive in time and memory, and each takes a unique random salt per password so identical passwords do not produce identical digests.
Never store a password as SHA-256, salted or not. The salt stops precomputed table lookups, but does nothing about the fact that a modern GPU can test billions of candidates per second.
Common questions
Can a hash be reversed?
Not by inverting it - hashes are one-way by design. But short or common inputs can be found by brute force or looked up in precomputed tables. An MD5 of a six-character password is effectively public knowledge. Hashing is not encryption and gives no confidentiality.
Is MD5 broken?
For security, completely. Practical collision attacks have existed since 2004 and can now be performed in seconds, and chosen-prefix collisions were demonstrated against SHA-1 in 2017 and again more cheaply in 2020. Both remain acceptable as non-adversarial integrity checks - verifying a file downloaded correctly - but must never be used for signatures, certificates or passwords.
Why can I not compute an MD5 of a huge file?
The file is read fully into memory to hash it, so very large files can exhaust what the browser tab is allowed to allocate. In practice files up to a couple of gigabytes usually work on a desktop; phones have far less headroom. If it fails, that is the reason.
Should I hash passwords with SHA-256?
No. Fast hashes are the wrong tool for passwords precisely because they are fast - a GPU can compute billions of SHA-256 hashes per second. Use a deliberately slow, memory-hard algorithm designed for the job - Argon2id, scrypt or bcrypt, each with a per-password salt.
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