How to Decode JWT Tokens Safely in the Browser
Inspect JWT headers and payloads during development without sending tokens to a third-party service.
Jun 3, 2026
JSON Web Tokens pack claims into a signed, URL-safe string. During API integration you need to read those claims — not guess them.
Never paste production secrets
Decode tokens locally. XSular Tools' JWT tool runs entirely client-side so credentials never hit our servers.
Read the three segments
A JWT has a header, payload, and signature separated by dots. The first two are Base64URL-encoded JSON; the signature verifies integrity.
Common debugging checks
- Expiry (
exp) vs current time - Issuer (
iss) and audience (aud) - Algorithm mismatch between header and server config
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