JWT Parser
The JWT Parser is a free online tool that decodes and inspects JSON Web Tokens (JWT) directly in your browser. Paste any JWT to instantly see its decoded header, payload, and signature — color-coded for clarity following the standard jwt.io convention.
The tool automatically detects token expiration, converts Unix timestamps to human-readable dates, and provides syntax-highlighted JSON output. All parsing is done client-side — no data is ever sent to any server, making it safe for use with production tokens.
How it works
A JWT consists of three Base64URL-encoded parts separated by dots: Header (algorithm and token type), Payload (claims like sub, iat, exp), and Signature (cryptographic verification). The parser decodes the first two parts and displays the signature hash.
Use cases
- Debugging authentication issues by inspecting token claims and expiration
- Verifying JWT payload contents during API development and testing
- Checking if a token has expired or will expire soon
- Understanding token structure for OAuth 2.0 and OpenID Connect integrations
- Inspecting custom claims added by your identity provider
Frequently asked questions
Is it safe to paste a JWT into an online parser?
With this tool it is, because all decoding happens client-side in your browser and no data is ever sent to a server. Even so, a decoded JWT reveals its full payload, so avoid pasting production tokens into parsers you do not trust. When in doubt, only use tools that clearly state parsing is local.
Can a JWT parser verify the token signature?
No. Decoding shows the header, payload, and signature hash, but verifying the signature requires the secret key or public key used to sign the token, which a decoder does not have. This parser confirms the token's structure and contents, not its cryptographic authenticity.
What are the three parts of a JWT?
A JWT has three Base64URL-encoded parts separated by dots: the header (which lists the signing algorithm and token type), the payload (which holds claims such as sub, iat, and exp), and the signature (used to verify the token was not tampered with). Only the header and payload are human-readable once decoded.
How do I check if a JWT is expired?
Look at the exp claim in the payload, which is a Unix timestamp for the expiration time. If that time is earlier than the current time, the token is expired. This parser converts exp automatically to a readable date and flags tokens that have already expired.
Why is my JWT payload readable without a password?
Because JWTs are encoded, not encrypted. Base64URL encoding only makes the data compact and URL-safe; anyone with the token can decode and read the payload. The signature protects against tampering, not against reading, so you should never store secrets like passwords in a JWT payload.