Test vector
For the ASCII input abc, SHA-256 produces exactly:
ba7816bf8f01cfea414140de5dae2223b00361a396177a9cb410ff61f20015adThe output always contains 64 lowercase hexadecimal digits, which They represent the 256 bits of the digest.
How the entry is interpreted
Before calculating the hash, the browser encodes the text as UTF-8. The accents, emojis and line breaks are part of the bytes, so any Change usually produces a different result. No space is removed beginning or end nor is Unicode normalized.
The empty string also has a SHA-256 defined. Press calculate without writing nothing to obtain its known vector; It is not considered an error.
What can check a hash
A digest allows you to compare whether two sequences of bytes look the same without directly display the content. It can be used to confirm a vector of test, detect accidental changes or contrast the value that documents a API.
To verify integrity against an attacker, the expected value must reach through a reliable channel. If someone can modify both the content and the published hash, the comparison does not offer authenticity. For authentication, They need constructs like HMAC or digital signatures and correct data management. keys.
Don’t use direct SHA-256 for passwords
SHA-256 is designed to be fast. This property allows testing many passwords per second. Password systems must use a function specific, slow and with unique salt per user, such as Argon2id, scrypt, bcrypt or PBKDF2 depending on the platform and its current policy.
This tool does not add salt, does not generate HMAC and does not read files. Calculate only SHA-256 of the entered UTF-8 text.
Unicode and line breaks
Two texts that look the same may have different Unicode normalization. Of
Likewise, LF and CRLF are different bytes. If you compare the result with
another system, confirms the coding, normalization and line terminator that
use each end.
The text comparator helps locate changes line by line. The Base64 converter represents bytes as text, but does not apply a hash and is reversible.
Privacy and limits
Web Crypto calculates the digest within the browser. The input is not transmitted, it is not stored and is not added to the URL. Up to 1,000,000 characters are supported; This version works with text, not large files or streams.
Frequently asked questions
Can text be recovered from SHA-256?
Not through a reverse operation. However, if the text belongs to a small or predictable set, someone can test candidates and compare their hashes.
Do uppercase and lowercase produce the same result?
No. They are different bytes. Spaces and line breaks also count.
Would the uppercase hexadecimal output be another hash?
No. It only changes the textual representation of the same 256 bits. This page Use lowercase letters consistently.
Technical references
SHA-256 is specified in NIST FIPS 180-4 and the operation of the browser at Web Cryptography Level 2.