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JWT Decoder

Decode and inspect JWT tokens

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About This Tool

JWT Decoder is an online tool that decodes JSON Web Tokens (JWT) into their three components β€” Header, Payload, and Signature. It automatically detects token expiration, displays decoded JSON with syntax highlighting, and lets you copy each part individually. All processing happens locally in your browser.

Key Features

Quick Preview

Use Cases

jwt token security

Frequently Asked Questions

What is a JWT token?

A JSON Web Token (JWT) is a compact, URL-safe way to represent claims between two parties. It consists of three Base64Url-encoded parts separated by dots: Header, Payload, and Signature. JWTs are commonly used for authentication and information exchange in web applications.

Does this tool verify the JWT signature?

No, this tool decodes the JWT to reveal its contents but does not verify the cryptographic signature. Signature verification requires the secret key or public key, which is not provided during decoding. The tool focuses on inspecting token claims and checking expiration status.

How does the expiration check work?

If the decoded payload contains an "exp" (expiration) claim, the tool compares it against the current time. A green indicator means the token is still valid, while a yellow warning shows the token has expired along with the exact expiration time.

Is my JWT token sent to any server?

No. All decoding happens entirely in your browser using JavaScript. Your JWT token is never transmitted to any server, which is especially important since tokens often contain sensitive authentication data.

Why does my token show an invalid format error?

A valid JWT must contain exactly three parts separated by two dots (e.g., xxxxx.yyyyy.zzzzz). If your token has fewer or more parts, or if the Header or Payload sections are not valid Base64Url-encoded JSON, the tool will display an error message explaining the issue.