RS512 JWT Decoder & Verifier
Paste an RS512-signed JWT to decode its claims. Enter the RSA public key (PEM or JWK) to verify the RSASSA-PKCS1-v1_5 + SHA-512 signature — locally, without any data leaving 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 RS512 in a JWT?
RS512 is RSASSA-PKCS1-v1_5 using SHA-512. It is the highest-hash-strength variant in the RSA JWT signing family. Like RS256 and RS384, it is an asymmetric algorithm using RSA private keys for signing and public keys for verification. The difference from RS256 is that SHA-512 is used to hash the data before the RSA signing operation.
On 64-bit servers, SHA-512 can be faster than SHA-256 due to its native 64-bit word operations, so RS512 does not necessarily carry a performance cost over RS256. The more significant cost is the RSA operation itself, which is the same regardless of which SHA-2 variant is used. RS512 is suitable for systems requiring the strongest available SHA-2 hash for signing.
Verify an RS512 JWT above by pasting the token and entering the RSA public key in the signature panel. The tool auto-detects the algorithm from the alg claim in the JWT header and uses SHA-512 in the RSASSA-PKCS1-v1_5 verification operation.
RS512 at a glance
- Full name
- RSASSA-PKCS1-v1_5 using SHA-512
- Algorithm family
- RSA (asymmetric)
- Signing key
- RSA private key (≥ 2048 bits)
- Verification key
- RSA public key (PEM or JWK)
- Signature size
- Equals key size (256 bytes for 2048-bit key)
- Security level
- ~112 bits (2048-bit 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.