HS512 JWT Decoder & Verifier
Paste an HS512-signed JWT to decode its claims. Enter your shared HMAC-SHA512 secret to verify the signature — the strongest symmetric JWT algorithm, verified locally in your browser.
100% in-browser — nothing uploadedEncoded JWT
Decoded Header
Paste a token to decode this segment.
Decoded Payload
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Verify Signature
Features
100% private
Your token is decoded entirely in your browser. Nothing is uploaded, logged, or sent to any server or API.
Instant decoding
Paste a JWT and the header, payload, and claims are decoded in real time — no button required.
Human-readable claims
Standard claims like exp, iat, and nbf are explained and shown as readable dates with expiry status.
Signature verification
Verify HS256/384/512 with a secret, or RS, PS, and ES algorithms with a public key — all client-side.
What is HS512 in a JWT?
HS512 is HMAC using SHA-512, the highest-strength member of the symmetric HMAC JWT algorithm family. It produces a 512-bit (64-byte) signature and provides a 256-bit security level — the same security level as AES-256 and the highest available for HMAC-based JWT signing. Like HS256 and HS384, it uses a shared secret for both signing and verification.
SHA-512 is notably fast on 64-bit processors because it operates on 64-bit words natively, making HS512 competitive with or faster than HS256 on modern server hardware despite its larger output. This makes HS512 an attractive option when you want the strongest HMAC option with no practical performance penalty on 64-bit systems.
To verify an HS512 JWT above, paste your token, go to the Signature tab, select HS512, and enter your secret. The recommended minimum key length is 512 bits (64 bytes) — generate one with openssl rand -base64 64. Everything runs in your browser via the Web Crypto API.
HS512 at a glance
- Full name
- HMAC using SHA-512
- Algorithm family
- HMAC (symmetric)
- Key type
- Shared secret (≥ 512 bits recommended)
- Signature size
- 512 bits (64 bytes)
- Security level
- 256 bits
- Verification key
- Same secret as signing key
How to decode a JWT token online
Paste your token
Copy a JSON Web Token and paste it into the encoded box. You can also load the example token to try it out.
Read the decoded data
The header and payload are decoded instantly. Switch to the Claims tab for plain-English explanations and expiry status.
Verify the signature
Enter the secret (HMAC) or public key (RSA/ECDSA) to confirm the token is authentic and hasn't been tampered with.