BLAKE2s hash
Compute a BLAKE2s digest of any file, on your device.
Runs on your device. The file is never uploaded.
BLAKE2s hash produces a 256 bit digest, 64 lowercase hex characters wide, from the 32-bit word variant aimed at smaller and embedded processors. hash-wasm's default length is what arrives, with no field to shorten it. A BLAKE2b digest cut down to 32 bytes is an unrelated value, so the two never stand in for each other.
Questions
How long is a BLAKE2s digest?
256 bits, or 64 lowercase hex characters, which is the hash-wasm default for this algorithm. The tool has no length option, so you cannot ask for a shorter or longer output on this page, and a value produced elsewhere at a different length will not match what you get here.
Why would I pick BLAKE2s over BLAKE2b?
Because something on the other side uses it. BLAKE2s is the 32-bit word variant, meant for smaller processors and embedded targets, and it turns up in firmware and constrained protocols. On a normal 64-bit machine BLAKE2b is the more natural fit.
Will BLAKE2s match BLAKE2b truncated to 256 bits?
No. They are separate algorithms with different word sizes, round counts and constants. Truncating a BLAKE2b digest to 32 bytes gives something completely unrelated to a BLAKE2s digest of the same file. Pick the one the other side uses, because there is no conversion between them.
Is this a checksum or a cryptographic hash?
A cryptographic hash. That distinction matters on this site, because CRC32, Adler-32 and the xxHash tools sitting near it are checksums built to catch accidental corruption and nothing more. BLAKE2s is designed to resist someone deliberately constructing a match, which is what makes it usable for integrity rather than only for error detection.
Does my file leave the browser?
No. The WebAssembly hash runs in a Web Worker in this tab and the file is never sent anywhere. You can disconnect from the network and keep hashing, because the whole site is cached after the first visit. There is no account and no upload step to opt out of.