SHA-256 hash generator and server seed checker

Type or paste text to see its SHA-256 and SHA-512 hash as you type. Everything runs in your browser with the Web Crypto API, and nothing is sent to our server.

A hash function turns any input into a fixed-length fingerprint. SHA-256 gives 64 hex characters and SHA-512 gives 128. The same input always gives the same hash, one changed character changes the whole result, and you cannot work backwards from a hash to the input.

Provably fair casinos use this to commit to your results before you bet. The casino picks a secret server seed and shows you only its SHA-256 hash. Each bet is generated from that server seed, your client seed and a nonce. When you rotate the seed, the casino reveals the server seed, and you can hash it here to confirm it is the one it committed to.

If the hash matches, the casino could not have swapped the seed after seeing your bets. To recalculate the bets themselves, use our verifier.

How to use it

Type or paste text into the box. The SHA-256 and SHA-512 hashes update as you type.
Use the copy button to copy a hash. Spaces and line breaks count, so paste exactly the text you want hashed.
To check a server seed, paste the revealed server seed and the hashed server seed the casino showed you before you played.
The checker hashes the seed with SHA-256 and SHA-512 and tells you whether either one matches. It ignores spaces at the start and end and the case of the hash.

Frequently asked questions

Is my text sent anywhere?

No. Your browser works out the hash with the Web Crypto API, and this page never sends what you type to our server, so you can paste a real server seed.

Why does my server seed not match the hash?

Make sure you copied the revealed server seed, not the client seed or the hash of the next seed. Some casinos use SHA-512 or their own scheme; each casino audit explains which one it uses.

Can a SHA-256 hash be reversed?

Not in practice. The only way to find the input for a hash is to guess inputs until one matches, and a random 64-character server seed has far too many possible values to guess.

What is the difference between SHA-256 and SHA-512?

Both belong to the SHA-2 family. SHA-256 gives a 256-bit hash shown as 64 hex characters, and SHA-512 a 512-bit hash shown as 128. Most casinos commit to the server seed with SHA-256; a few, such as Thrill, use SHA-512.

Key terms

Server seed: The casino's secret random value that, together with your client seed and the nonce, decides each bet result.
Hashed server seed: The SHA-256 digest of the casino's secret server seed, published before any bet as proof the seed is locked in.
Client seed: The player's own input to every provably fair result, set or edited by you so the casino cannot work out outcomes in advance.
Provably fair: A cryptographic method that lets you confirm a game result was set before your bet and left untouched afterwards.

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