HMAC Calculator
Compute HMAC-SHA1, SHA-256, SHA-384, or SHA-512 over a message and secret — for API signing or message auth.
Algorithm
🔒 Secrets and messages are processed entirely in your browser via SubtleCrypto.
About this tool
Uses the browser's native SubtleCrypto.sign with HMAC. Output is shown in hex (most common for HTTP signatures) and Base64 (often used inside JSON tokens).
Need to verify an HMAC? Generate one from the same key and message and compare. Use the existing comparison field to do it without eyeballing 64 hex chars.
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