EdDSA JWT Decoder & Verifier
Paste an EdDSA-signed JWT to decode its claims. Enter the Ed25519 public key (PEM or JWK) to verify the signature — modern, fast, and secure, 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 EdDSA in a JWT?
EdDSA (Edwards-curve Digital Signature Algorithm) in the JWT context refers to Ed25519, the most widely adopted Edwards-curve variant. Ed25519 uses Curve25519 and SHA-512 internally to produce 64-byte signatures from 32-byte (256-bit) keys. It is designed to be fast, secure, and resistant to common implementation pitfalls that affect RSA and ECDSA.
Unlike ECDSA (ES256), EdDSA is deterministic — signing the same payload with the same key always produces the same signature. This eliminates the risk of nonce reuse vulnerabilities that have historically plagued ECDSA implementations. Ed25519 also has very fast key generation and signing operations, making it attractive for high-throughput systems.
EdDSA is defined in RFC 8037 for use with JWTs. Its JWK representation uses kty: OKP (Octet Key Pair) and crv: Ed25519. Paste an EdDSA JWT above and enter the Ed25519 public key in the Signature tab to verify locally. Browser support via the Web Crypto API is available in modern browsers.
EdDSA at a glance
- Full name
- Edwards-curve Digital Signature Algorithm (Ed25519)
- Algorithm family
- EdDSA (asymmetric)
- Curve
- Curve25519 / Ed25519
- Key size
- 32 bytes (256-bit private key, 32-byte public key)
- Signature size
- 64 bytes (deterministic)
- Security level
- ~128 bits
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.