SHA256 generator
The SHA-256 digest appears here as you type
Hashed in your browser · the file is never uploaded
SHA-256 produces a 256-bit digest, written as 64 hexadecimal characters. It is the default choice for almost everything that needs a hash today: certificate signatures, Git object names in newer repositories, file checksums, and the proof-of-work in Bitcoin.
How to generate a SHA-256 hash
A frequent misunderstanding is worth naming: SHA-256 is not encryption. Encryption is reversible with a key; hashing is not reversible at all. Nobody can decrypt a SHA-256 digest, and any site offering to do so is running a lookup table of previously-hashed common inputs. That is also the reason SHA-256 alone is unsuitable for storing passwords. It is fast, so an attacker can try billions of candidates a second against a stolen database.
Questions
256 bits, shown as 64 hexadecimal characters. The length never changes, no matter how large the input.
No, and not because it is difficult. The information is genuinely gone. Sites claiming to decrypt it are looking the digest up in a table of common inputs.
No. There is no known practical attack on either its collision or preimage resistance.
Not on its own. Use bcrypt, scrypt or Argon2, which are deliberately slow and salted.
That is the avalanche property working as intended: any change to the input should produce an unrelated digest.