JWT Inspector
Paste a token and see exactly what it claims and when it dies.
BeginnerWeb appDev tool4–10hAI-buildable 5/5no setupworth shipping
Decode a JSON Web Token into its header, payload and signature, with timestamps rendered as readable dates and expiry status called out. Everything stays local. A small tool you'll use constantly once you have it.
UI
Logic
Useful
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Core features · 7
- Paste a token and see header and payload decoded
- The three segments are colour-coded in the raw token
- Timestamp claims render as readable dates with relative time
- Expired tokens are clearly flagged
- Malformed tokens report exactly which segment failed
- Standard claims are labelled with their meaning
- Decoding happens entirely locally, and the UI says so
The interesting part
- Base64url decoding differs from standard base64
- Distinguishing a malformed token from one that is merely unfamiliar
- Making it obvious that decoding is not the same as verifying
Once it works
- Add signature verification with a provided key
- Add a token builder alongside the decoder
- Add a diff between two tokens
Suggested stack
reacttypescripttailwind