JWT Decoder

Decode and analyze JSON Web Tokens (JWT) with detailed header, payload, and signature breakdown. Free JWT decoder tool for developers and security professionals.

About JWT and Token Decoding

JSON Web Token (JWT) is a compact, URL-safe means of representing claims to be transferred between two parties. JWTs are widely used for authentication, authorization, and secure data exchange in modern web applications. Each JWT consists of three parts: a header, a payload, and a signature, separated by dots. The header specifies the algorithm and token type, the payload contains the claims, and the signature ensures the token's integrity.

Decoding a JWT allows you to inspect its contents without needing the secret key. However, verifying the signature requires the secret. This tool helps you decode and analyze JWTs for debugging, development, and security review purposes.

JWTs are commonly used in OAuth 2.0, OpenID Connect, and many single sign-on (SSO) systems. Understanding the structure and claims of a JWT is essential for secure application development and troubleshooting authentication issues.

How This Tool Works

The JWT Decoder tool processes your token directly in your browser. When you paste a JWT, the tool splits it into its three parts, decodes the header and payload from Base64Url, and displays the results. If the token is invalid or cannot be parsed, an error message is shown. The signature is displayed as-is, since verification requires the original secret key.

All processing happens locally-no data is sent to any server, ensuring your privacy and security. The tool is optimized for speed and works on all modern devices and browsers.

Use this tool for safe, instant JWT inspection during development, debugging, or learning about token-based authentication.

Key Features

  • Instant Decoding: Paste a JWT and see the decoded header, payload, and signature immediately.
  • Error Highlighting: Get clear error messages for invalid or malformed tokens.
  • Expiration Check: See if the token is active or expired, and how much time is left.
  • Privacy First: All processing is done locally in your browser-no data leaves your device.
  • Responsive Design: Works seamlessly on desktop and mobile devices.
  • Accessibility: Keyboard and screen reader friendly for all users.
  • Free & Unlimited: No registration, no limits, always free to use.

These features make this JWT Decoder an essential tool for developers, testers, and anyone working with token-based authentication.

Common Use Cases

  • Debugging Authentication: Inspect JWTs during OAuth, OpenID Connect, or SSO flows.
  • Security Audits: Analyze token claims and expiration for vulnerabilities.
  • Learning & Teaching: Demonstrate JWT structure and claims in educational settings.
  • API Development: Test and debug JWT-based authentication in RESTful APIs.
  • Token Migration: Convert or update tokens during system upgrades or migrations.
  • Documentation: Create readable JWT examples for technical docs and tutorials.

Whether you are a developer, security analyst, or student, this tool streamlines your workflow and helps you avoid common JWT pitfalls.

Step-by-Step Guide

  1. Paste Your JWT: Enter or paste your JWT token into the input area above.
  2. View Decoded Data: Instantly see the header, payload, and signature.
  3. Check Expiration: If the token has an expiration claim, see if it is active or expired.
  4. Review Claims: Inspect all claims in the payload for debugging or documentation.
  5. Fix Errors: If you see an error, review the message and correct your token.
  6. Repeat as Needed: You can use the tool as many times as you like for different tokens.

For best results, ensure your JWT is properly formatted. This tool is designed to help you learn and work efficiently with JWTs, no matter your experience level.

Frequently Asked Questions

  • Is my data safe? Yes, all processing is done locally in your browser. No data is sent to any server.
  • Can I use this tool offline? Yes, once loaded, the tool works without an internet connection.
  • Does it support all JWT types? The tool supports standard JWTs, but some custom or encrypted tokens may not decode properly.
  • What if my token is invalid? The tool will show an error message and highlight the issue so you can fix it.
  • Is this tool free? Absolutely! There are no usage limits or fees.
  • Can I share decoded data? Yes, you can copy the result and share it as needed.
  • What browsers are supported? All modern browsers, including Chrome, Firefox, Edge, and Safari.
  • Who can use this tool? Anyone! It's designed for developers, security professionals, students, and anyone who works with JWTs.

If you have more questions or suggestions, please contact us. We are always looking to improve and expand our tools based on user feedback.