JWT Decoder and Inspector

Use this JWT Decoder and Inspector to inspect the contents of a JSON Web Token directly in your browser. It is useful when you need to debug authentication flows, check token claims, review expiration times, or understand the structure of a JWT returned by an API or identity provider.

This tool decodes the token locally and helps you review the header, payload, and standard time-based claims in a readable format.

What Is a JWT?

A JWT, or JSON Web Token, is a compact token format commonly used for authentication and authorization. A JWT usually contains three dot-separated parts:

• header
• payload
• signature

The header and payload are Base64URL-encoded JSON objects, while the signature is used to verify integrity.

What This Tool Helps You Do

This tool is designed for inspection, not trust verification. It helps you:

• decode the JWT header
• decode the JWT payload
• inspect claims such as iat, exp, and nbf
• review expiration timing in ISO date form
• examine the raw token segments

Important Note

Decoding a JWT is not the same as verifying it. A token can be decoded even if the signature is invalid. This tool is useful for debugging and inspection, but it does not replace server-side verification.

Common Use Cases

• Debugging login and refresh-token flows
• Checking whether a token has expired
• Inspecting claims from OAuth or OpenID Connect providers
• Reviewing audience, issuer, or subject fields during API work
• Explaining JWT structure to teammates

Example

A JWT typically looks like this:

eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9.eyJzdWIiOiIxMjM0NTYiLCJuYW1lIjoiQWxpY2UiLCJleHAiOjE3MzU2ODk2MDB9.signature

This tool helps you decode the first two segments into readable JSON so you can inspect the token quickly.

Frequently Asked Questions

Does this tool verify the JWT signature?

No. It decodes the token locally for inspection, but it does not verify the signature against a secret or public key.

Can I use this with expired tokens?

Yes. It can still decode expired tokens so you can inspect their claims.

What claims are especially useful to inspect?

Common claims include iat, exp, nbf, iss, aud, and sub.

Related Tools

• Base64 Encoder & Decoder
• Online JSON Encoder
• JSON Formatter / Minifier
• DateTime Converter

Final Thoughts

JWTs show up constantly in modern authentication workflows. A local decoder and inspector helps you debug tokens quickly, understand claim data, and spot timing issues without sending sensitive values to another service.