JWT Decoder Online Free

Key Features

When Do You Need a JWT Decoder?

JWT tokens are used for authentication in virtually every modern web application. When debugging auth issues, you need to inspect the token's contents — what claims it contains, when it expires, what algorithm was used, and what user data is encoded. This tool makes that instant. Instead of writing base64 decode code or using curl commands, just paste the token and see all the information clearly formatted.

Benefits

• •Debug authentication issues in web applications quickly
• •Verify token claims match expected values
• •Check token expiration without writing code
• •Inspect algorithm and key ID in the header
• •Understand JWT structure for learning purposes
• •Validate tokens during API development and testing

How to Decode a JWT

1. 1Copy your JWT token from your app, browser DevTools, or API response
2. 2Paste the full token into the input field
3. 3Click 'Decode JWT' to process the token
4. 4View the header section (algorithm and token type)
5. 5View the payload section (claims, user data, expiration)
6. 6Check if the token is expired — shown with a red warning

Understanding JWT Structure

A JWT consists of three parts separated by dots: Header.Payload.Signature. The header contains the algorithm (alg) and token type (typ). The payload contains claims — standard claims like sub (subject), exp (expiration), iat (issued at), and custom claims like user ID and roles. The signature verifies the token hasn't been tampered with. This tool decodes the header and payload but cannot verify the signature without the secret key.

Frequently Asked Questions

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