JWT tools for decoding tokens and checking expiry claims
JWT problems usually come down to the visible claims: issuer, audience, subject, scopes, roles, issue time, and expiry. These tools make those values easy to inspect, while keeping the distinction clear between decoding a token and verifying a token.
Tools in this workflow
API & Auth
OpenJWT Decoder
Decode JWT headers and payloads, inspect claims, and check expiry fields at a glance.
API & Auth
OpenJWT Expiry Checker
Show whether a JWT is expired, valid, or missing expiry claims with readable timestamps.
Encoders & Decoders
OpenBase64 Encode / Decode
Encode plain text to Base64 or decode Base64 back to readable text with Unicode support.
Converters
OpenTimestamp Converter
Convert Unix seconds, Unix milliseconds, and ISO date strings with readable UTC and local output.
Related guides
How to decode a JWT token
Learn how to decode JWT header and payload claims in the browser, read exp and iat values, and avoid common token mistakes.
How to encode and decode Base64
Understand Base64 encoding, decode strings safely in the browser, and connect decoded output to JSON, JWT, and file workflows.
How to convert Unix timestamp to date
Convert Unix seconds or milliseconds into readable dates and understand timezone differences in API logs and JWT claims.
Common JWT Security Mistakes Developers Should Avoid
A developer checklist for JWT algorithms, expiry, issuer, audience, signature verification, token storage, and safe debugging.
FAQ
Does decoding a JWT prove it is valid?
No. Decoding only shows the header and payload. Signature verification and claim validation must happen in the backend or trusted verification code.
What should I inspect first in a JWT?
Check exp, iss, aud, scopes, and roles first. Those claims explain many 401 and 403 failures during API debugging.