what's wrong with the built in one?

https://developer.mozilla.org/en-US/docs/Web/API/SubtleCrypt...

Requires a secure origin. If you serve a local (but non-localhost) SPA over HTTP then you're blocked from using crypto.subtle.digest. At least, that is one reason I have seen a hand-rolled SHA-256 deployed.

Edit: oh, and it forces async.

no incremental hashing, so you can't hash files too large for ram.

I do use it for smaller files though, it's much faster.