HMAC generator

Calculate a SHA-256 HMAC from a UTF-8 message and key.

On your device · No account

Privacy details

HMAC generator processes your input in this browser. Inputs and results are excluded from analytics. Recent tools save tool names, visit counts and last-visit times. Saved tools store only their names. Draft saving is optional and stays on this device; delete saved text with the draft controls. Loading text from a URL is optional and contacts that server; its URL and your IP address are visible to the server. An optional “Use in” action keeps a handoff in this tab. The next tool removes it on arrival and ignores it if more than a minute has passed.

Copy link includes the inputs you choose to share in the address. Anyone with that link can reopen them. Files and generated results are excluded. Password and key tools share settings only.

Message

More options

Key (UTF-8 text)

Your result

Reset reloads the tool with its starting values and releases open files and device controls. Saved drafts stay on this device until you delete them.

Links include your inputs and settings. Anyone with the link can see them, so leave out private text. Files and generated results are left out; random draws run again.

Keyboard shortcuts

Updated 2026-09-19

Using HMAC generator

HMAC generator signs the exact message bytes with the supplied text key using the browser’s Web Crypto implementation. Spaces, newlines and Unicode are part of the message.

Next: JWT generator

A worked example

The example key “key” and the displayed fox sentence produce the hex HMAC beginning f7bc83f4.

Before you use the result

This accepts the key as UTF-8 text, not hex or Base64. HMAC authenticates a message; it does not encrypt it. Avoid entering production keys into a general-purpose web page.

Cite this page

Citation style

ToolOctopus. “HMAC generator.” Updated 2026-09-19. https://tooloctopus.com/hmac-generator.

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