JWT Decoder
Decode JSON Web Tokens (JWT) and inspect header, payload, and signature. Pretty-printed JSON output. All processing is local. Free, private, browser-based.
No server uploads • 100% browser-based • Your token never leaves your device
How It Works
1 Paste Token
Copy and paste any JWT into the input field. The tool accepts standard three-part tokens separated by dots.
2 Decode
Each part is base64url-decoded. The header and payload are parsed as JSON and displayed with syntax highlighting.
3 Inspect
Review the algorithm, token type, claims, and signature. All processing stays in your browser — nothing is sent to any server.
Frequently Asked Questions
What is a JWT?
JWT (JSON Web Token) is an open standard for securely transmitting information as a JSON object. It consists of three parts: header, payload, and signature, separated by dots.
Is my JWT uploaded to a server?
No. All JWT decoding happens entirely in your browser. Your token never leaves your device.
Does this tool validate the signature?
This tool decodes and displays the three parts of a JWT. Signature validation is not performed — use the JWT Generator tool for development and testing with signature support.
What does base64url decoding mean?
JWTs use a URL-safe variant of Base64 encoding (base64url) that replaces + and / with - and _, and strips padding. This tool handles that conversion automatically.
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