SHA3-256 hash
Compute a SHA3-256 digest of any file, on your device.
Runs on your device. The file is never uploaded.
SHA3-256 hash reads a file and returns a 64 character lowercase hex digest, 256 bits wide, from the Keccak sponge. hash-wasm's sha3 is called with a fixed 256, so no other length is reachable from this page. The FIPS 202 padding suffix means it never equals a Keccak-256 digest, the value Ethereum tooling produces.
Questions
Is SHA3-256 the same thing as SHA-256?
No. They share a digest length and nothing else. SHA-256 is SHA-2, built on a Merkle-Damgard compression function; SHA3-256 is the Keccak sponge standardised as FIPS 202 after a public competition. The same file gives two completely different 64 character digests, so the two are never interchangeable in a comparison.
How long is the output?
256 bits, or 64 lowercase hex characters. The tool calls hash-wasm sha3 with a fixed 256-bit size, so there is nothing to configure and no way to ask for a different length here. The digest prints on the line after the title and your file name.
Should I move from SHA-256 to SHA3-256?
There is no urgency. SHA-256 has no public collision attack, and SHA-3 was standardised as a structurally different backup rather than as a replacement for something failing. Use SHA3-256 when a protocol, an audit or a counterpart asks for it by name, and stay with SHA-256 when compatibility with existing tooling matters more.
Why does my blockchain tool give a different value?
Because most of that world uses Keccak-256, the pre-standard version, not SHA3-256. FIPS 202 added a domain separation suffix before padding, which changes every digest. Use the Keccak-256 tool for Ethereum style hashing and this one for FIPS 202 SHA-3.
Can I hash more than one file?
Yes. Each file dropped is hashed separately and returns its own two line result: the title with your file name, then the digest. Nothing is uploaded at any point, and the WebAssembly hashing runs in a Web Worker in this tab, so a large file does not lock up the page while it works.