JWT Decoder
Decode JSON Web Tokens instantly. See the header, payload, and signature with syntax highlighting, standard claim explanations, expiration checking, and timestamp formatting. Free. No sign-up.
How it works
- 1Paste your JWT
Paste a JWT token into the input field. The tool auto-decodes on paste, showing the header, payload, and signature instantly.
- 2Inspect the decoded data
Switch between Header, Payload, and Signature tabs. See syntax-highlighted JSON with explanations for every standard claim like iss, sub, exp, and iat.
- 3Check expiration and copy
The expiration badge tells you if the token is valid or expired. Timestamps are formatted to human-readable dates. Copy any section with one click.
Why You Need a JWT Decoder
JSON Web Tokens are the de facto standard for authentication and authorization in modern web applications. Every time a user logs in, a JWT is typically issued containing claims about the user, their permissions, and the token's validity period. Debugging authentication issues, verifying token contents, and checking expiration times are daily tasks for developers working with JWTs.
A JWT decoder saves time by instantly parsing the three parts of a token — header, payload, and signature — into readable JSON. Instead of manually Base64-decoding each section, you paste the token and see everything at once. The syntax highlighting makes it easy to scan claim names and values, while the standard claim explanations help you understand what each field means without looking up the RFC.
The expiration check is particularly valuable during debugging. A common authentication bug is an expired token that should have been refreshed. The red or green badge tells you immediately whether the token is still valid, and the relative time display shows exactly when it expired or when it will expire. Timestamp claims like iat, exp, and nbf are automatically converted from Unix timestamps to human-readable dates.
All processing happens entirely in your browser. Your JWT tokens are never sent to a server, never logged, and never stored. This is important because JWTs often contain user IDs, email addresses, roles, and other sensitive information. The tool runs on JavaScript and works offline once the page has loaded.