RS256 JWT Decoder & Verifier
Paste an RS256-signed JWT to decode its header and payload. Enter the RSA public key (PEM or JWK) to verify the signature — the most widely used asymmetric JWT algorithm, verified client-side.
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 RS256 in a JWT?
RS256 stands for RSA using PKCS #1 v1.5 padding with SHA-256. It is an asymmetric signing algorithm: the private key (held only by the token issuer) is used to sign, and the corresponding public key (freely distributable) is used to verify. This separation means any service can verify RS256 tokens by fetching the issuer's public key from a JWKS endpoint, without ever having access to the signing key.
RS256 is the most widely deployed JWT signing algorithm. Auth0, Google, Microsoft (Azure AD), Firebase, and dozens of other identity providers default to RS256. The public keys are published as JSON Web Key Sets (JWKS), typically at a URL like /.well-known/jwks.json. The kid claim in the JWT header identifies which key in the JWKS was used to sign.
RS256 requires RSA key pairs of at least 2048 bits (3072 or 4096 bits for higher security). To verify an RS256 JWT above, fetch the public key from the issuer's JWKS, select the key matching the kid, and paste the PEM-encoded public key or the raw JWK into the signature panel. Verification runs locally using the browser's Web Crypto API.
RS256 at a glance
- Full name
- RSASSA-PKCS1-v1_5 using SHA-256
- 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.