SHA-256 Generator and Hash Lookup
Understanding SHA-256
SHA-256 is the most widely used SHA-2 variant. It produces a 256-bit digest, written as 64 hexadecimal characters, and is used for file verification, signatures, content identification and many security protocols.
Digest size256 bits
Common format64 hexadecimal characters
Generation and database lookup
The generator calculates SHA-256 from the exact input bytes. Database lookup is not decryption: it checks whether an identical digest was previously associated with a plaintext in our corpus. You can submit up to 20 hashes in one request.
Worked example
The SHA-256 digest of hello is 2cf24dba5fb0a30e26e83b2ac5b9e29e1b161e5c1fa7425e73043362938b9824. A single changed bit, capital letter or line ending produces a completely different digest.
How does the lookup work?
Our index is optimized for exact matching and multi-algorithm batches. A result can be free or offered as a one-time unlock according to a dynamically calculated complexity score; the plaintext is never sent to the browser before payment confirmation.
Security guidance
SHA-256 remains suitable for integrity and cryptographic constructions designed around it. It should not be used directly for password storage because its speed allows huge numbers of guesses. Use a salted, deliberately expensive password KDF.
Reproduce the calculation
These examples hash exactly the text “hello” without a trailing newline. A space or line break would change the digest.
Shell
printf %s 'hello' | sha256sumPHP
echo hash('sha256', 'hello');JavaScript
const bytes = new TextEncoder().encode('hello');
const digest = await crypto.subtle.digest('SHA-256', bytes);Comparison with other SHA variants
SHA-256 has twice the output length of MD5 and avoids the known collision failures of MD5 and SHA-1. SHA-512 uses 64-bit words and a 512-bit output; on some 64-bit processors it can even be faster than SHA-256.
FAQ
How many characters are in SHA-256?
A SHA-256 digest contains 64 hexadecimal characters, or 32 bytes and 256 bits.
Can SHA-256 be decrypted?
No. The service performs a matching lookup in previously calculated corpora.
Is SHA-256 safe for password storage?
Not by itself. It is too fast against offline guessing; use Argon2id, scrypt or bcrypt with a unique salt.
What is SHA-256 used for?
It is used for integrity checks, signatures, content identification and many cryptographic protocols.
Why do two tools produce different SHA-256 values?
They probably hashed different bytes: encoding, whitespace, capitalization, BOMs and line endings all change the result.
Practical notes
SHA-256 remains suitable for integrity checks and signatures when used in a sound protocol. Passwords should instead use a slow KDF such as Argon2id, scrypt or bcrypt.
Length256 bits / 64 hex
BatchUp to 20 digests
ModesHash, file and HMAC
Frequently asked questions
Does SHA-256 encrypt data?
No. It produces a one-way digest and cannot restore the original content.
What is the difference between SHA-256 and HMAC-SHA-256?
HMAC combines SHA-256 with a secret key and is commonly used to authenticate a message.
Can two files be compared?
Calculate each file digest and compare the exact hexadecimal strings.
Reproducible examples
These commands hash the five UTF-8 bytes in “hello”, without adding a trailing newline.
Terminal
printf %s "hello" | sha256sumPHP
hash('sha256', 'hello');JavaScript
const bytes = new TextEncoder().encode('hello');
const digest = await crypto.subtle.digest('SHA-256', bytes);