What is a JWT?
A JSON Web Token has three Base64URL-encoded parts: header, payload, and signature. This tool decodes the first two so you can inspect claims — it does not verify the signature.
JWT Decoder
Paste a JWT to instantly decode its header and payload as readable JSON.
How it works
- 1
Paste the value to encode or decode.
- 2
Pick the direction / algorithm if the tool has modes.
- 3
Copy the output. Decoding is not the same as verifying a signature.
Why use this tool
- Runs entirely in your browser — nothing is uploaded to a server.
- 100% free, no sign-up, no limits.
- Works in any modern browser — no app install, no extension, no account.
How to use JWT Decoder
Use JWT Decoder to transform encodings in your browser. If you decode a JWT or similar token, that does not prove the signature is valid.
Tips for better results
Watch for padding and character-set issues. Never paste production secrets into a shared screen.
Privacy and offline-friendly processing
Whenever possible, JWT Decoder processes your data locally with JavaScript in this page. That means drafts, secrets, and unfinished work stay on your device by default. Prefer this workflow when you do not want to upload sensitive text, tokens, passwords, or files to a third-party service.
Frequently asked questions
Does this verify the token signature?
No, this tool only decodes and displays the header and payload; it does not verify the signature or trust the token.
Is my token sent anywhere?
No, decoding happens entirely in your browser using JavaScript.
Is my data uploaded when I use this tool?
For most FlyUtils tools, no. Processing happens in your browser with JavaScript. If a tool ever needs a server, that will be stated clearly on the page.
Is JWT Decoder free to use?
Yes. JWT Decoder is free, with no sign-up and no artificial usage caps for normal personal and work use.
Does JWT Decoder work on mobile?
Yes. The page is mobile-first, so you can paste input, tweak options, and copy results from a phone or tablet.