JWT Decoder/Encoder
Decode, encode, and verify JWTs with advanced features.
Introduction
JWT Decoder/Encoder is a safe workspace for inspecting tokens, understanding claims, and validating signatures before integrating with gateways or APIs.
Readable header/payload views reduce guesswork, while premium verification ensures integrity using HS/RS/ES algorithms and your provided keys.
Key features
- Decode JWT header, payload, signature
- Syntax highlighting and validation
- Copy decoded payload
- Show algorithm/type/claims
- Token expiry/issued-at display
- Load sample JWT
- Clear/reset editor
- Help panel with examples, shortcuts, tips, accessibility
How it works
Tokens are split into header, payload, and signature. Decoding runs locally in your browser. Signature verification (premium) runs inside the app with your provided secret or public key, returning a clear valid/invalid result and expiration status.
Step-by-step usage
- Paste a JWT into the editor.
- Inspect header and payload; confirm iss/aud/sub and exp/iat.
- (Premium) Select algorithm, provide key, and verify signature.
- Copy decoded data or (premium) create/sign a new token.
Examples
Decode a JWT payload
Paste the token; read exp, iss, and aud.
Check expiration
Confirm exp is in the future and nbf (if present) is in the past.
(Premium) Verify signature
Select HS256, provide the shared secret, and verify the signature is valid.
Security & privacy
Where applicable, processing runs locally in your browser. Inputs are not logged or sent to external services. Premium features inside the app use Supabase Auth to protect access. For sensitive work, prefer local files and avoid sharing secrets. Outputs include copy and download actions to minimize manual transcription errors.
Accessibility
The tool supports keyboard navigation and screen readers with ARIA labels and descriptive messages. Focus order is logical, and error messages use human‑readable language. These docs maintain proper heading hierarchy and color contrast, and the app version includes skip links and live regions where appropriate.
Limitations & disclaimers
Some advanced capabilities are available only in the DevToolsKitHub app with a premium plan. The static documentation does not execute code or store inputs. Where behaviors differ across runtimes (browsers, servers, language engines), treat outputs as representative examples.
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