JWT Decoder

Decode JWT header and payload claims instantly in your browser.

What this tool does

Decode JSON Web Tokens (JWT) to inspect header and payload claims for debugging and integration checks.

Tool interface

Input

Output

Example input

eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9.eyJzdWIiOiIxMjM0NTY3ODkwIiwibmFtZSI6IkFuYSIsImlhdCI6MTUxNjIzOTAyMn0.SflKxwRJSMeKKF2QT4fwpMeJf36POk6yJV_adQssw5c

Example output

{
  "header": {
    "alg": "HS256",
    "typ": "JWT"
  },
  "payload": {
    "sub": "1234567890",
    "name": "Ana"
  }
}

Step-by-step instructions

  1. Paste your full JWT in header.payload.signature format.
  2. Click Transform to decode token sections.
  3. Review header and payload claims, then copy or download the decoded JSON.

Common use cases

  • Validating and formatting API payloads during debugging.
  • Transforming JSON into spreadsheet-friendly formats.
  • Cleaning JSON files before using them in applications.

Helps developers troubleshoot auth flows by quickly inspecting JWT contents without external tooling.

Common mistakes to avoid

  • Assuming decoding means token signature verification.
  • Sharing production tokens in unsafe channels while debugging.
  • Ignoring `exp`, `iat`, and `aud` claims during auth investigations.

Frequently Asked Questions

Does this verify JWT signatures?

No. This tool decodes token content only and does not verify signatures.

Is my token uploaded?

No. Decoding happens in your browser.

Can I inspect expired tokens?

Yes. Expired tokens can still be decoded for troubleshooting claim values.

What input format does JWT Decoder expect?

Use valid JSON input unless the tool explicitly asks for path or pattern syntax first.

What does JWT Decoder output?

It returns transformed output you can copy or download as `decoded-jwt.json`.

Why might JWT Decoder return an error?

A common issue is: Assuming decoding means token signature verification.

Does JWT Decoder run in the browser?

Yes. Transformations are designed for in-browser usage so you can test and iterate quickly.

Can I copy or download results from JWT Decoder?

Yes. You can copy the result or use the download action when file output is available.

Related tools

Related guides

Browse all DataToolbox guides for more workflows.

Related categories

Looking for other utilities in this area? JSON Tools, Developer Data Tools