JWT Decoder | Online JSON Web Token Parser & Inspector
Decode. Inspect. Understand. • 100% Client-Side • Human-Readable Claims
Our **Premium JWT Decoder & Inspector** is a developer-first tool for parsing and understanding JSON Web Tokens. Unlike basic decoders, we provide **human-readable explanations** for standard claims, automatic conversion of Unix timestamps (exp, iat, nbf) to your local time, and a live **Expiry Status** tracker. Your tokens are processed 100% in your browser—never sent to any server—ensuring maximum privacy and security. ### JWT Algorithm Comparison Common algorithms for signing JWTs:
| Algorithm | Description | Security Level |
|---|---|---|
| HS256 | HMAC using SHA-256 (Symmetric) | High (requires shared secret) |
| RS256 | RSASSA-PKCS1-v1_5 using SHA-256 (Asymmetric) | Very High (Private/Public Key) |
| ES256 | ECDSA using P-256 and SHA-256 | Highest (Modern, efficient) |
How to Use
- Paste your encoded JWT (header.payload.signature) into the input area.
- The tool will instantly color-code the token parts (Header, Payload, Signature).
- View the decoded JSON objects in the interactive panels.
- Check the **Claim Inspector** table for plain-English explanations of each claim.
- Monitor the **Expiry Badge** for the token's validity and remaining time.
- Use the **NLP Power Bar** to ask questions like "Is this token expired?" or "Who is the issuer?".
Features
- Instant 100% Client-Side Decoding: No data ever leaves your browser.
- Human-Readable Timestamps: Automatic conversion of `exp`, `iat`, and `nbf` claims.
- Live Validity Tracking: Real-time "EXPIRED" or "Valid" status badges.
- Claim-by-Claim Education: Tooltips explaining standard claims like `sub`, `iss`, `aud`, `jti`.
- Color-Highlighted Input: Visual distinction between JWT segments.
- NLP Power Search: Natural language query support for token properties.
- History Tape: Securely store your last 5 decoded tokens for debugging sessions.
- Copy-to-Clipboard: One-click copying for Header, Payload, or the entire token.
Common Use Cases
- API Debugging: Quickly verifying the claims and scopes in your Authorization header tokens.
- Security Auditing: Checking if tokens have correct expiration and audience values.
- Development: Inspecting OAuth2 and OIDC tokens during integration.
- Learning: Understanding how JWTs work and what common claims represent.
- Privacy-Conscious Workflow: Decoding production tokens without sending them to third-party servers.
Tips & Best Practices
JWTs are Base64Url encoded, not encrypted. Never store sensitive secrets in the payload.
Always check the `alg` header to ensure it matches your expected algorithm (e.g., RS256).
The `exp` claim is in seconds (Unix time). Our tool converts this for you automatically.
If a token fails to decode, ensure you haven't included the "Bearer " prefix from the Auth header.
Use the History Tape to switch between access and refresh tokens during debugging.
Common Questions
Is it safe to paste my production tokens here?
Yes. Our JWT Decoder performs all decoding strictly within your browser using JavaScript. No token data is ever transmitted to our servers or stored externally. Your privacy and security are our top priorities.
What is the difference between Header, Payload, and Signature?
A JWT has three parts: The Header (algorithm and token type), the Payload (data/claims about the user), and the Signature (used to verify the token hasn't been tampered with).
Why is my token marked as EXPIRED?
A token is expired if its "exp" (expiration) timestamp is in the past. Expired tokens should be rejected by your API for security reasons.
What do claims like sub, iss, and aud mean?
"sub" is the Subject (user ID), "iss" is the Issuer (who created the token), and "aud" is the Audience (intended recipient). Our Claim Inspector provides detailed tooltips for these.