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Generate HMAC (Hash-based Message Authentication Code) for API authentication.
HMAC Generator is a free online generator that lets you generate HMAC (Hash-based Message Authentication Code) for API authentication. It runs entirely in your browser — no account creation, no software installation, and no data uploaded to external servers. This makes it a practical choice for anyone who needs to generate and customize security & privacy tools-related values quickly and privately. Whether you are a professional working through a daily task list, a student checking homework figures, or a freelancer preparing a deliverable, HMAC Generator gives you an instant result you can copy, screenshot, or feed into the next step of your workflow. ToolPeg hosts this tool alongside security & privacy tools tools and 300+ other free utilities so you always have a single bookmark for everyday browser-based tasks.
Many ToolPeg tools process inputs locally, but tools that work with public URLs, domains, or network-facing information should still be treated as working with public-facing data.
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The secret key is used to authenticate the message. Keep it secure and share it only with trusted parties.
HMAC output will appear here
About HMAC
HMAC (Hash-based Message Authentication Code) is a mechanism for verifying both the data integrity and authenticity of a message. It combines a cryptographic hash function (SHA-256 or SHA-512) with a secret key. HMACs are commonly used in API authentication, JWT token signing, webhook verification, and secure data transmission. Unlike plain hashing, HMAC requires the secret key to verify the message, preventing unauthorized tampering. This tool uses the native Web Crypto API for secure computation.
| Property | HMAC-SHA-256 | HMAC-SHA-512 |
|---|---|---|
| Output Size | 256 bits (64 hex chars) | 512 bits (128 hex chars) |
| Block Size | 64 bytes | 128 bytes |
| Security Level | 128-bit (strong) | 256-bit (very strong) |
| Performance | Faster (optimized for 32-bit) | Faster on 64-bit CPUs |
| Common Uses | JWT, API auth, webhooks | High-security applications |