JWT Token Decoder
Decode JWT tokens instantly. View header, payload, and signature as formatted JSON. Color-coded sections with time field interpretation. Free, client-side.
Why Use the JWT Decoder?
JWT tokens are everywhere in modern web applications for authentication and data exchange. Debugging JWTs requires decoding the Base64-encoded header and payload. Our tool instantly decodes JWTs with color-coded sections and automatic time field interpretation.
Key Features
- Color-coded header (red), payload (violet), and signature (teal) sections
- Automatic interpretation of time fields (iat, exp, nbf) as human-readable dates
- Visual token structure breakdown showing all three parts
- Copy buttons for each decoded section independently
How to Use
- Paste your JWT token in the input area
- The token is automatically decoded into header, payload, and signature
- View formatted JSON output and time interpretations
Technical Details
JWT tokens consist of three Base64URL-encoded parts separated by dots: header.payload.signature. The header specifies the algorithm, the payload contains claims, and the signature is used for verification. This tool only decodes — it does not verify the signature. Base64URL encoding uses - instead of + and _ instead of /, with no padding.
FAQ
Does this tool verify the JWT signature?
No, this tool only decodes the token. Signature verification requires the secret key or public key, which is not provided to a client-side decoder for security reasons.
Is my JWT token sent to any server?
No. All decoding happens entirely in your browser. Your JWT token never leaves your device.
Related articles
Base64 in Plain Words: What It Is and What It's For
What a string like SGVsbG8sIHdvcmxkIQ== means, why Base64 is not encryption, and where it appears: email, JWT, data URIs. Encode and decode online in seconds.
JWT tokens: what's hiding behind “eyJhbGciOi…” and how to read it
What a JWT is made of, why tokens start with “eyJ”, how a signature differs from encryption, where to check expiry, and why secrets don't belong in the payload.
Related tools
Base64 Encode / Decode
Encode text to Base64 or decode Base64 strings with full Unicode support
URL Encode / Decode
Encode and decode URLs with full or component encoding modes
Encoding Detector
Detect text and file encoding online: UTF-8, UTF-16, ASCII, Windows-1251, KOI8-R. Confidence score, byte details and a side-by-side preview of how the text looks in each candidate encoding
HTML Entity Encode / Decode
Encode and decode HTML entities like < > & "
ROT13 Cipher
Encode or decode text using the ROT13 substitution cipher
Morse Code Translator
Convert text to Morse code and back with visual representation and audio playback