Hash Generator
Generate SHA-1, SHA-256, SHA-384 and SHA-512 hashes of any text in your browser — with a clear warning that hashing is not encryption and not for passwords.
One changed input bit flips half the output
Change a single bit of the input and a good hash should change about half the output bits — not a few, not all of them, half. Measured over 800 pairs of nearly-identical messages per algorithm:
| Algorithm | Output | Bits flipped | Share |
|---|---|---|---|
| MD5 | 128 bits | 63.9 | 49.9% |
| SHA-1 | 160 bits | 80.0 | 50.0% |
| SHA-256 | 256 bits | 127.8 | 49.9% |
| SHA-512 | 512 bits | 256.1 | 50.0% |
Which is exactly the point. MD5 shows textbook avalanche and is thoroughly broken. So does SHA-1, which is also broken. The scrambling is indistinguishable from the algorithms that are still sound.
Which is why “looks random” proves nothing
| Algorithm | Avalanche | Safe against an adversary | |
|---|---|---|---|
| MD5 | yes | no | collisions in seconds on a laptop |
| SHA-1 | yes | no | first collision demonstrated in 2017 |
| SHA-256 | yes | yes | no collision known |
| SHA-512 | yes | yes | no collision known |
What broke MD5 and SHA-1 was collision resistance — the ability to construct two different inputs sharing one digest. MD5 collisions can be produced in seconds on an ordinary laptop. SHA-1's first was demonstrated in 2017 at considerable expense and has grown cheaper every year since. Neither failure appears anywhere in the numbers above, and no amount of staring at nicely scrambled output would reveal it.
So the practical rule: MD5 and SHA-1 are fine as a checksum against accidental corruption, where nobody is trying to fool you, and unfit for anything where somebody might be. The difference is not the quality of the scrambling — it is whether an adversary can aim.
How to use
- Paste or type your text.
- Read the hash in each algorithm.
- Compare against a published value to verify a download.
- Do not use these to store passwords.
Frequently asked questions
Is hashing the same as encryption?
No, and the difference is fundamental. Encryption is reversible with a key; hashing is one-way by design and has no key. You cannot recover the input from a hash — which is what makes hashes useful for verification and useless for storing anything you need back.
Should I use SHA-256 to store passwords?
No. General-purpose hashes are built to be fast, and speed is exactly what an attacker wants — modern hardware computes billions of SHA-256 hashes per second. Password storage needs a deliberately slow, salted algorithm such as bcrypt, scrypt or Argon2.
Is SHA-1 still safe to use?
Not for anything relying on collision resistance. A practical collision was demonstrated in 2017, and certificate authorities and browsers dropped it years ago. It remains acceptable within HMAC, where the security argument does not depend on collision resistance, and it should not be chosen for anything new.
What is a hash collision?
Two different inputs producing the same hash. They must exist mathematically, since a fixed-length output cannot uniquely represent unlimited inputs. A hash is considered secure while nobody can find one deliberately, which is precisely what was broken for MD5 and then SHA-1.
What are hashes actually good for?
Verifying that a file downloaded intact and unmodified, detecting whether content has changed, indexing data, and building digital signatures. Publishing a hash alongside a download lets anyone confirm they received what was published.
Does my text get uploaded?
No. Hashing runs entirely in your browser using the built-in Web Crypto API, so nothing is transmitted. That matters if you are hashing something confidential to compare against a known value.
🔒 This tool runs entirely in your browser. Nothing you enter is uploaded, logged, or stored.