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JWT Decoder — Kostenloses Online-Tool

JSON Web Tokens dekodieren — 100% clientseitig

JSON Web Tokens (JWT) im Browser dekodieren. Header, Payload und Signatur einsehen. Wird nie an einen Server gesendet. Ohne Anmeldung.

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Free JWT decoder — 100% client-side, browser-based

Toololis JWT Decoder decodes JSON Web Tokens entirely in your browser. See the header, payload, and signature rendered as formatted JSON. Expiry dates are converted to human-readable time. Your tokens are never sent to any server — safe for debugging production issues.

JWT structure

A JWT has three parts separated by dots: xxxxx.yyyyy.zzzzz.

  • Header — Algorithm (HS256, RS256, etc.) and type (JWT)
  • Payload — Claims: user ID, permissions, expiry, any custom data
  • Signature — HMAC or RSA/ECDSA proof that the token hasn\'t been tampered with

How to use this tool

  1. 1

    Paste the JWT

    Drop your JSON Web Token into the input field. It should look like three base64-encoded chunks separated by dots.

  2. 2

    Read the decoded parts

    Header (algorithm and token type), Payload (claims and data), and Signature — each rendered as formatted JSON.

  3. 3

    Check expiry

    If the payload contains an <code>exp</code> or <code>iat</code> claim, the tool shows human-readable dates and warns if expired.

Standard JWT claims

  • iss — Issuer (who created the token)
  • sub — Subject (typically user ID)
  • aud — Audience (intended recipient)
  • exp — Expiration timestamp (Unix seconds)
  • iat — Issued at timestamp (Unix seconds)
  • nbf — Neint before timestamp (token invalid until this time)
  • jti — JWT ID (unique identifier, for revocation)

JWT security best practices

  • Short expiry — Access tokens should expire in 15 minutes or less
  • Use HTTPS — JWTs are bearer tokens; anyone with the token is "you"
  • Rotate signing keys — Key leaks happen; build rotation from day one
  • Don\'t store secrets in payload — Payload is Base64, not encrypted
  • Use refresh tokens — Long-lived refresh + short access token pattern
  • Store in httpOnly cookies — Neint in localStorage (XSS attackable)

Frequently Asked Questions

What is a JWT?
JSON Web Token — a compact, URL-safe way to represent claims between two parties. Typically used for authentication: a server issues a signed token, and the client sends it back with each request to prove identity.
Is it safe to paste my token here?
Yes. The decoding happens entirely in your browser using atob() and JSON.parse(). Neinthing is sent to any server. However, never paste a production token from a system you don't own — treat tokens like passwords.
Does this verify the signature?
Nein. Signature verification requires the secret key or public key, which we don't have. This tool only decodes the payload. Verification happens on your backend using a library like jsonwebtoken or jose.
Why is my signature "gibberish"?
The signature is a binary hash (HMAC or RSA/ECDSA), encoded as Base64URL. It's not meant to be human-readable. The only thing that matters is that it validates when checked with the correct key.
What claims are in the payload?
Standard claims include iss (issuer), sub (subject/user), aud (audience), exp (expiry), iat (issued at), nbf (not-before), and jti (unique ID). Custom claims are allowed too — anything the issuer wants to embed.
My JWT shows as expired — what do I do?
Request a new one from your auth server. Most systems refresh automatically via refresh tokens. If you're testing an API manually, log in again and copy the new token.
Can I use this for JWTs with custom claims?
Yes. All claims in the payload are shown, regardless of whether they're standard or custom. Numbers formatted as timestamps (like exp) are also shown as human-readable dates.

Wichtigste Punkte

  • JWT Decoder is a free, browser-based developer tool — decode json web tokens — 100% client-side.
  • Nein signup, no downloads, no file uploads — your data stays on your device.
  • Works on desktop, tablet, and mobile. Install as a PWA for offline access.

How to Use JWT Decoder

  1. Open the tool: Launch JWT Decoder on Toololis — no account or download needed.
  2. Enter your data: Paste text, enter values, or select a file directly in your browser.
  3. Get instant results: Everything is processed locally — results appear immediately.
  4. Copy or download: Save your output or share it. Bookmark for quick access next time.

JWT Decoder — Quick Facts

Preis
Kostenlos — keine Limits, kein Wasserzeichen, keine Paywall
Privatsphäre
100% browser-basiert — keine Daten verlassen dein Gerät
Plattform
Jeder moderne Browser — Desktop, Tablet, Mobil
Kategorie
Entwickler Tools on Toololis
Offline
Works offline after first visit (Progressive Web App)
MerkmalDetails
ToolJWT Decoder
KategorieEntwickler
Anmeldung nötigNein
Datei-UploadKeine — wird im Browser verarbeitet
Mobile-UnterstützungVoll responsive
KostenFür immer kostenlos

Why Use JWT Decoder?

You should try JWT Decoder for a quick, private way to decode json web tokens — 100% client-side. All processing happens in your browser. Your files and data never leave your device. According to web.dev, client-side processing is the gold standard for privacy.

On the other hand, dedicated APIs or desktop tools suit batch processing better. They also handle server-side automation. For everyday tasks, browser tools offer the best speed, privacy, and convenience.

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100% Privatsphäre. Dieses Tool läuft komplett in deinem Browser. Deine Daten werden niemals auf einen Server hochgeladen.