Generate SHA-1, SHA-256, SHA-384, and SHA-512 hashes — free, no sign-up, nothing leaves your browser.
A cryptographic hash takes any input — a word, a paragraph, an entire file — and always produces an output of the same fixed length, no matter how large the input was. The same input always produces exactly the same hash, but there's no way to reverse the process and recover the original input from the hash alone. Even a tiny change to the input — one character, one bit — produces a completely different-looking hash with no visible relationship to the original, a property sometimes called the avalanche effect. This is what makes hashes useful for checking that a downloaded file hasn't been corrupted or tampered with: compare the hash of the file you received against the hash the publisher provided, and if even a single byte differs, the two hashes won't match.
MD5 is considered cryptographically broken and isn't supported by browsers' built-in hashing — this tool only uses natively supported, currently-secure algorithms (SHA-1 is included for compatibility with older systems, though SHA-256 or higher is recommended for anything security-sensitive).
SHA-256 is a solid general-purpose default, widely used and considered secure. SHA-384 and SHA-512 offer a larger output for slightly more resistance against certain theoretical attacks, at no real practical cost for most uses. SHA-1 should only be used where an older system specifically requires it.
Yes — the whole file is read and hashed locally in your browser, so very large files may take a moment and use some memory, but nothing is uploaded anywhere.
Even a difference invisible to the eye — a different line-ending style, extra whitespace, a changed timestamp embedded in the file, or a different file format saved from the same content — will produce a completely different hash, since the algorithm operates on the exact bytes, not the visual content.
No. All hashing happens locally in your browser — nothing you enter or upload is sent to a server.