JWT Decoder - Inspect JSON Web Tokens
Decode JWT tokens and inspect header, payload, and expiration claims.
Processed 100% locally in your browser. Tokens never leave your device.
About JWT Decoder - Inspect JSON Web Tokens
Splits JWT strings into header.payload.signature parts and Base64-decodes each segment for inspection.
What Can You Use This Tool For?
Software engineers, web developers, and API designers use JWT Token Decoder to format production data, debug network requests, validate syntax errors, and streamline daily coding workflows without risking data leaks.
How to Decode JSON Web Tokens
1. Paste an encoded JWT string (header.payload.signature).
2. The decoder splits and parses the Base64URL header and payload claims.
3. Inspect expiration timestamps (exp), issuer (iss), subject (sub), and custom claims.
Usage Examples
Decoding JWT Payload Claims
Input: eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9.eyJzdWIiOiIxMjM0NTY3ODkwIiwibmFtZSI6IkFsaWNlIiwiaWF0IjoxNTE2MjM5MDIyfQ... Decoded Payload: { "sub": "1234567890", "name": "Alice", "iat": 1516239022 }
Frequently Asked Questions
Can I use this JWT Token Decoder offline without an internet connection?
Yes, once the web page is loaded in your browser, all parsing and code processing execute client-side using JavaScript without requiring active server connections.
Does Numvax log, save, or transmit my code/data?
Never. Numvax operates under a strict client-side privacy architecture. All operations execute strictly inside your local browser memory.
Is there a file size or character limit for this tool?
There is no artificial limit. The tool can process payloads as large as your device memory and browser can handle.
Is this JWT Token Decoder free for commercial use?
Yes, all Numvax developer tools are 100% free for personal, educational, and commercial development workflows with no subscriptions or accounts required.
Does this tool verify the JWT signature key?
This tool decodes and displays token headers and payload claims client-side for debugging. Signature verification requires your private secret key.
Is my auth token safe?
Yes. Token decoding occurs 100% locally in your browser. Tokens are never sent to external servers.
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