About SHA-256 Hash Generator
This SHA-256 hash generator computes the SHA-256 digest of your text or file. SHA-256 produces a 256-bit value, written as 64 hexadecimal characters. It is free, needs no sign-up and runs in your browser, so nothing you enter is uploaded.
SHA-256 is the default choice today. It belongs to the SHA-2 family, has no known practical attack, and is built into every browser, operating system and programming language. It protects TLS certificates, signs software releases, and links the blocks in Bitcoin, where it is applied twice.
The digest comes from the Web Crypto API in your browser. The hash is computed as UTF-8, so the text "café" is hashed as five bytes, not four. To hash a file instead, switch the input to File, choose the file and compare the result with the value on the download page. To use SHA-256 with a secret key, tick HMAC with secret key.
Changing one character changes the whole digest. "Hello, World!" gives dffd6021bb2bd5b0af676290809ec3a53191dd81c7f70a4b28688a362182986f, and dropping the exclamation mark gives 03675ac53ff9cd1535ccc7dfcdfa2c458c5218371f418dc136f2d19ac1fbe8a5. The two digests look unrelated.
SHA-256 is fast by design, which makes it the wrong choice for storing passwords. Use bcrypt or Argon2 in your application for that. This tool does not offer them.
How to use SHA-256 Hash Generator
- Choose an algorithm from the row of buttons: MD5, SHA-1, SHA-224, SHA-256, SHA-384, SHA-512, SHA3-256, SHA3-512 or CRC32. SHA-256 is a good default.
- Choose Text and type or paste your input, or choose File and pick a file from your device. The hash updates as you type.
- Read the digest in the result box. Tick Uppercase for capital hex letters, or Base64 output to show the digest in Base64 instead of hex.
- For a keyed hash, tick HMAC with secret key and enter the key. The result is then labelled HMAC-SHA-256 (or whichever algorithm you chose).
- To verify a download or a value from documentation, paste the expected hash into Compare with a known hash. The tool says Match or No match.
- Use Copy to put the digest on your clipboard.
Features
- Nine algorithms: MD5, SHA-1, SHA-224, SHA-256, SHA-384, SHA-512, SHA3-256, SHA3-512 and CRC32.
- Hashes text as UTF-8, so accented letters, other scripts and emoji hash the same way as on a server or in a command-line tool.
- Hashes a file you choose from your device. The file is read in your browser and never uploaded.
- HMAC with a secret key for every algorithm except CRC32, following RFC 2104.
- Hex output in lowercase or uppercase, or Base64 output.
- Compare with a known hash. Case, spaces and a leading 0x are ignored, and the expected value can be hex or Base64.
- SHA-1, SHA-256, SHA-384 and SHA-512 use the Web Crypto API in your browser, which is fast and well tested.
- A warning appears when you pick MD5, SHA-1 or CRC32, because they are not safe for security purposes.
- One-click copy of the result.
Worked examples
SHA-256 of "abc" gives ba7816bf8f01cfea414140de5dae2223b00361a396177a9cb410ff61f20015ad
The FIPS 180 test vector.
SHA-256 of "hello" gives 2cf24dba5fb0a30e26e83b2ac5b9e29e1b161e5c1fa7425e73043362938b9824
SHA-256 of "Hello, World!" gives dffd6021bb2bd5b0af676290809ec3a53191dd81c7f70a4b28688a362182986f
SHA-256 of "Hello, World" (no exclamation mark) gives 03675ac53ff9cd1535ccc7dfcdfa2c458c5218371f418dc136f2d19ac1fbe8a5
Privacy: how it works
- The text, the file and the HMAC key stay in your browser tab. Nothing is sent to Ulkaa or to any other server, which you can confirm in the Network tab of your browser developer tools.
- Because the work happens on your own device, large files are limited by your browser memory rather than by an upload limit.
Tips
- To verify a download, choose File, pick the downloaded file, and paste the publisher hash into the compare box. A match means the bytes are identical to what the publisher hashed.
- Hash the same text twice with a trailing space added once. Seeing two unrelated digests is the quickest way to understand the avalanche effect.
- A hash you found on the same page as the download only protects against corruption. It cannot protect you if the page itself was altered.
- HMAC takes the key as plain text. If your key is hex or Base64, decode it first, or the result will not match another system.
Frequently asked questions
Is it really free?
Yes. There is no price, no trial and no credit card. Ulkaa Tool does the work with your own device, so there is no server bill to pass on to you.
Do I need an account?
No. There is no sign-up and no login. Open the page and use it. An Ulkaa account is not needed for anything on this tool.
Does it run in my browser?
Yes. Your text and files are processed by code running in your browser tab, on your own device.
Is my data uploaded?
No. Your text and files are never sent to Ulkaa or to anyone else. You can check this yourself by watching the Network tab in your browser developer tools while you use the tool.
Can a SHA-256 hash be reversed?
No. A hash function is one-way. The same input always gives the same hash, but the hash does not reveal the input. Short or common inputs can be guessed by trying them, which is why SHA-256 alone is wrong for passwords.
How long is a SHA-256 hash?
It is 256 bits, which is 64 hexadecimal characters, or 44 characters in Base64 with padding.
How do I check the SHA-256 of a download?
Switch to File, pick the file, then paste the SHA-256 shown on the download page into the compare box. A Match result means the file is byte for byte what the publisher hashed.
More Hash Generator pages
- Hash GeneratorHash text or a file with MD5, SHA-1, SHA-2, SHA-3 or CRC32, add an HMAC key, and check the result against a known hash.
- MD5 Hash GeneratorGet the 128-bit MD5 hash of text or a file as 32 hexadecimal characters.
- SHA-1 Hash GeneratorGet the 160-bit SHA-1 hash of text or a file as 40 hexadecimal characters.
- SHA-224 Hash GeneratorGet the 224-bit SHA-224 hash of text or a file as 56 hexadecimal characters.
- SHA-384 Hash GeneratorGet the 384-bit SHA-384 hash of text or a file as 96 hexadecimal characters.
- SHA-512 Hash GeneratorGet the 512-bit SHA-512 hash of text or a file as 128 hexadecimal characters.
- SHA3-256 Hash GeneratorGet the 256-bit SHA3-256 hash of text or a file as 64 hexadecimal characters.
- SHA3-512 Hash GeneratorGet the 512-bit SHA3-512 hash of text or a file as 128 hexadecimal characters.
- CRC32 Checksum CalculatorCalculate the 32-bit CRC32 checksum of text or a file as 8 hexadecimal characters.
- HMAC-SHA256 GeneratorSign a message with a secret key using HMAC-SHA256 and read the result as hex or Base64.
- File Checksum CalculatorHash a file on your device and compare it with the checksum the publisher gave you.