What is a JWT Decoder?
The JWT Decoder is an advanced security tool that unpacks JSON Web Tokens. It separates and decodes the Header and Payload of the token, allowing developers to inspect claims, user IDs, and expiration dates in a human-readable JSON format.
JSON Web Tokens (JWT) are heavily used in modern web authentication. They look like gibberish strings of random characters separated by dots. When debugging login systems, developers need to verify exactly what data is inside the token. This tool safely decodes the token instantly without needing the secret key.
How to Use JWT Decoder
- 1
Paste your full JSON Web Token string into the top input field.
- 2
The tool will instantly parse the token and split it into Header, Payload, and Signature.
- 3
Review the Header to see the algorithm used (e.g., HS256).
- 4
Review the Payload to inspect claims like `sub`, `iat`, and `exp`.
- 5
The tool automatically converts Unix timestamps into human-readable browser dates.
Features
- 100% Free: Unlimited use without any hidden fees or premium locks.
- No Signup: Instantly start using the utility without registering an account.
- Works in Browser: Fully client-side processing natively in your web browser.
- No Data Stored: Your inputs are not saved, logged, or recorded on any server.
- Mobile Friendly: Perfect responsive design for smartphones and tablets.
- Instant Results: Lightning fast execution with zero loading screens.
Examples
eyJhbG.eyJzdWI.SflKxw (A standard three-part token)
{"alg": "HS256", "typ": "JWT"}
{"userId": 123, "role": "admin", "exp": 173110290}
Frequently Asked Questions
Is this tool free?
Yes, it is entirely free for unlimited decoding.
Is my data safe?
Extremely safe. JWTs contain authentication secrets. Our tool decodes them entirely client-side in your browser.
Does it work on mobile?
Yes, fully responsive on all mobile devices.
Can this tool verify the signature?
No, this tool only decodes the Base64Url encoded segments. Verifying the cryptographic signature requires your private backend secret key, which should never be pasted online.
Why do I see a timestamp number?
JWT uses Unix Epoch time (seconds since 1970). Our interface automatically formats this into a standard date and time for you.