HMAC-SHA512 Generator Online — Maximum Security Message Authentication
HMAC-SHA1 · HMAC-SHA256 · HMAC-SHA384 · HMAC-SHA512 · Webhook verify · Batch · API signing · 100% browser-side
🔒 Key never leaves your browser — processed via Web Crypto API
Enter message + secret key to generate HMAC
HMAC-SHA256 · HMAC-SHA512 · Real-time · Web Crypto API
HMAC-SHA512 provides the strongest HMAC security — a 512-bit (128 hex char) signature. Ideal for banking APIs, fintech systems, and any application requiring maximum message authentication security. Supports all key formats and verify mode.
What is HMAC?
HMAC (Hash-based Message Authentication Code) is a cryptographic technique that combines a hash function with a secret key. Unlike a plain hash which only verifies data integrity, HMAC also proves authenticity — only someone with the correct secret key can produce a valid HMAC. It is the backbone of API authentication, webhook verification, and JWT signatures.
HMAC-SHA256 vs HMAC-SHA512
HMAC-SHA256 is the current industry standard — used by AWS Signature V4, GitHub webhooks, Stripe, Shopify, and most modern REST APIs. It produces a 64-character hex signature. HMAC-SHA512 provides extra security with a 128-character hex signature and is preferred for banking, fintech, and high-security systems. Both are secure — choose SHA256 for compatibility and SHA512 for maximum security.
Frequently Asked Questions
When should I use HMAC-SHA512?
Use HMAC-SHA512 for banking APIs, high-value financial transactions, government systems, and any application where SHA256 is considered insufficient. Both are currently secure.
Is HMAC-SHA512 faster than HMAC-SHA256?
On 64-bit CPUs, HMAC-SHA512 is often faster than HMAC-SHA256 because SHA-512 is natively 64-bit. On 32-bit systems, SHA-256 is faster.
How long is a HMAC-SHA512 signature?
HMAC-SHA512 produces 128 hexadecimal characters (512 bits = 64 bytes = 128 hex chars) or 88 characters in Base64.
Can I use HMAC-SHA512 for JWT?
Yes. JWT HS512 algorithm uses HMAC-SHA512. Set the JWT header to {"alg":"HS512","typ":"JWT"} and use this tool to compute the signature.
HMAC-SHA384 vs HMAC-SHA512?
HMAC-SHA384 is a truncated version of SHA-512 (384 bits). It offers slightly better performance than SHA-512 with similar security. SHA-512 is more commonly supported.