Decode, inspect, encode, and verify JSON Web Tokens instantly with header, payload, signature, expiration, and HS256 validation.
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How to Use the JWT Tool
The JWT Decoder & Encoder helps you inspect and work with JSON Web Tokens directly in your browser.
You can paste a token to decode its header, payload, and signature, check timing fields
like exp, iat, and nbf, and verify an HS256 signature if you have the secret key.
To decode a token, paste it into the JWT field and the tool will automatically read the token structure. The header and payload will be
shown in readable JSON format, while the signature will appear separately. If the payload contains expiration or issued time claims,
the tool will also display a clear timing summary and a live countdown when applicable.
You can also edit the payload JSON and generate a new token using HS256. This makes the tool helpful for
development, debugging, QA workflows, API testing, and learning how JWT tokens are structured.
What This JWT Tool Can Do
Decode JWT tokens into readable header and payload JSON
Encode new JWT tokens using HS256
Verify signatures with a provided secret key
Show expiration status and live countdown
Read iat and nbf claims in human time format
Copy token and payload quickly
Work in browser without sending data to a server
Important Note
JWT payloads are usually encoded, not encrypted. That means anyone with the token can often read the header and payload.
Never place highly sensitive secrets directly in a JWT payload. For real production systems, always follow secure token handling,
key management, and backend validation practices.
Frequently Asked Questions (FAQ)
A JWT, or JSON Web Token, is a compact token format used to transfer claims between systems.
It usually contains a header, payload, and signature separated by dots.
Yes. The header and payload of a standard JWT can usually be decoded without the secret key because they are Base64URL encoded.
The secret key is only needed for signature generation and verification in HS256.
Yes. This tool can verify HS256 signatures when you provide the correct secret key.
The verification result will show whether the signature matches or not.
The exp claim means expiration time. It tells you when the token should no longer be accepted.
This tool converts it into a readable date and also shows whether the token is still valid or expired.
iat means issued at, which tells you when the token was created.
nbf means not before, which tells you the earliest time the token should be accepted.
No. This tool is for standard JWT inspection and HS256 verification. Encrypted token formats such as JWE require different handling.
No. JWT payloads are usually readable by anyone who has the token. Sensitive secrets should not be stored directly in the payload.
No. The tool works in your browser, which helps keep the token data local on your device.