JWT-Decoder

So verwendest du JWT-Decoder

1. 1Enter or paste your data into the input field.
2. 2Select the desired encoding, hashing, or encryption options.
3. 3Click the action button to process your data.
4. 4Copy the result from the output field.

Funktionen

• ✓100% kostenlos — keine Registrierung, kein Abo, keine Werbung
• ✓Läuft vollständig im Browser — Daten verlassen niemals dein Gerät
• ✓Schnell und ressourcenschonend — sofortige Ergebnisse
• ✓Plattformübergreifend — Desktop, Tablet und Smartphone

Was ist JWT-Decoder?

JSON Web Token (JWT), defined by RFC 7519, is a compact, URL-safe token format for securely transmitting claims between parties. A JWT consists of three Base64URL-encoded parts separated by dots: Header.Payload.Signature. It is widely used for API authentication, OAuth 2.0, and SSO.

Wie funktioniert JWT-Decoder?

The Header specifies the signing algorithm (e.g., HS256, RS256). The Payload contains claims (registered, public, private) — statements about an entity. The Signature is computed over the encoded Header and Payload using the algorithm and a secret/private key. To verify, recompute the signature and compare.

Typische Anwendungsfälle

• ✓API authentication — bearer tokens in Authorization headers
• ✓OAuth 2.0 — access tokens and ID tokens
• ✓SSO — share identity across multiple services
• ✓Stateless sessions — store user info without server-side sessions

JWT vs Session Cookies

Sessions store state server-side; JWTs are stateless and self-contained. JWTs scale better (no session store) but are harder to revoke before expiry. Sessions are more secure for sensitive apps (can revoke instantly); JWTs suit distributed/microservice architectures. Always use HTTPS for both.

Sicherheit & Datenschutz

This tool decodes JWTs locally in your browser — your token never leaves your device. IMPORTANT: Decoding a JWT only reads its contents; it does NOT verify the signature. Never trust JWT claims without server-side signature verification. JWTs are visible to anyone who intercepts them — use HTTPS.

Technische Details

Standard: RFC 7519. Structure: Base64URL(Header).Base64URL(Payload).Base64URL(Signature). Header: alg (HS256/RS256/ES256/none), typ. Registered claims: iss (issuer), sub (subject), aud (audience), exp (expiry), nbf (not before), iat (issued at), jti (JWT ID). Signature: HMAC(SHA-256) for HS256, RSA for RS256. 'alg: none' tokens must always be rejected.

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