JWT Decoder – Decode JWT Tokens Online
Decode JWT headers and payloads into readable JSON without signature verification. Our free JWT Decoder is the fastest way to inspect token claims during development and debugging.
What is a JWT?
You have a JWT from an authentication response and need to see what's inside. The token is just a long string of characters that's actually Base64-encoded JSON. You want to read the claims, check expiration, or verify the user info without making API calls.
What This Tool Does
Header Display
View algorithm and token type
Payload Claims
Read user data and metadata
Expiration Check
See if token is expired
Local Processing
Tokens stay in your browser
Security Notice
This tool decodes JWT tokens without verifying their signature. Do not use this to validate authentication tokens. For educational and debugging purposes only.
About JSON JWT Decoder
JWT tokens contain encoded JSON data that needs to be inspected during development. This decoder splits the token into its three parts and displays the header and payload as readable JSON. No server-side processing, everything happens in your browser.
How JWT decoding works
Paste your JWT token in the input box. The tool splits it by dots into header, payload, and signature sections. Each Base64URL-encoded part is decoded and parsed as JSON, then displayed in its own card with syntax highlighting.
The header shows the algorithm and token type. The payload displays claims like user ID, expiration, and custom data. The signature is shown as raw Base64URL. Invalid tokens show an error message.
When you'd use this
You're debugging authentication issues and need to see what's in a JWT. Or you received a token from an API and want to verify its contents before using it. This tool also helps when learning how JWTs are structured.
This decoder only reads token contents, it doesn't verify signatures. Don't trust decoded data without proper verification in your application. Never paste production tokens with sensitive data into online tools.
Questions
What are the three parts of a JWT?
Header (algorithm info), Payload (claims/data), and Signature (verification). Each is Base64URL-encoded and separated by dots.
Can this verify token signatures?
No, this only decodes and displays contents. Signature verification requires the secret key and should happen server-side.
Is it safe to decode tokens here?
The decoding happens locally in your browser. However, avoid pasting tokens with sensitive data or production credentials.
What if my token is invalid?
Invalid tokens will show an error. Common issues include wrong format, corrupted Base64, or missing parts.
Can I decode expired tokens?
Yes, decoding works regardless of expiration. The exp claim will show the token is expired but the data is still readable.