HMAC Generator
Generate keyed-hash message authentication codes (HMAC) using SHA-256 or SHA-512 algorithms online.
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Compute keyed-hash message authentication codes (HMAC) online for API payload signing, webhook verification, and data integrity checks. This tool accepts your message payload, a shared secret key, and your choice of cryptographic hash algorithm to compute a message digest. You can select either SHA-256 or SHA-512 depending on your protocol specifications or signature verification requirements. When you provide non-empty text and select a supported algorithm, the interface generates the corresponding hex-encoded HMAC string immediately. If the text input is left empty, the output panel remains empty. If you submit a text string without providing a secret key, the tool applies an internal fallback secret to compute the hash. Use this utility to verify webhook signatures from third-party services, test authentication headers during API development, or validate cryptographic implementations against known test vectors without writing custom calculation scripts.
Instructions
- Enter or paste your raw payload or message into the Text field.
- Enter your shared secret key into the Secret field.
- Choose your target cryptographic algorithm (SHA-256 or SHA-512) from the Algorithm dropdown.
- Review the generated hexadecimal HMAC hash displayed in the output area.
Examples
- Calculate an HMAC-SHA256 signature for the message 'order_id=10842' using the secret key 'api_secret_key_44'.
- Generate an HMAC-SHA512 checksum for a JSON webhook payload '{"event":"payment.completed","id":9201}' using a shared signing key.
FAQ
Which hash algorithms are supported by this HMAC generator?
The generator supports SHA-256 and SHA-512 algorithms for computing keyed-hash message authentication codes.
What happens if I leave the text field empty?
When the text input is empty, no HMAC calculation takes place and the output remains empty.
What happens if I leave the secret key field blank?
If you provide text but leave the secret empty, the tool uses an internal fallback secret to generate the digest.
In what format is the generated HMAC returned?
The resulting message authentication code is provided as a standard hexadecimal string.