HMAC Generator
Generate HMAC signatures using SHA-256, SHA-512, or MD5 with a secret key.
Frequently Asked Questions
Why does a hex key sometimes throw an error?
Hex mode only accepts hexadecimal characters and it requires an even number of digits. Spaces are ignored, but an odd-length key is rejected.
What's the difference between using UTF-8 text and Hex key modes?
They turn the key into bytes differently. The text `616263` in UTF-8 mode means six ASCII characters, while in Hex mode it becomes the three bytes `61 62 63`.
Why do I get a signature even when the message is blank?
That is valid HMAC behavior. If you provide a key, the tool can sign an empty string and still produce a correct digest.
Should I compare the hex output or the Base64 output?
Either is fine as long as your other system expects the same encoding. They represent the same HMAC bytes in two different text formats.
How is this different from the regular hash generator?
A hash only digests the message. HMAC digests the message together with a secret key, which is why it is used for signatures and shared-secret verification.