Base64Fix.ai — JWT Tools
Decode JWT Base64 Safely — Client-Side Only
JWTs contain sensitive data. Decode yours safely — everything happens in your browser, never on our servers.
🔒 Decode My JWT NowWhat Is a JWT?
A JSON Web Token (JWT) is a compact, URL-safe token format used for authentication and authorisation. It consists of three Base64URL-encoded parts separated by dots:
eyJhbGciOiJIUzI1NiJ9.eyJzdWIiOiJ1c2VyXzEyMyJ9.SflKxwRJSMeKKF2QT4fwpMeJf36POk6yJV_adQssw5c
Header
Algorithm & token type
Payload
Claims (user ID, roles, expiry)
Signature
HMAC or RSA — verified server-side only
Why Client-Side JWT Decoding Matters
Most online JWT decoders send your token to a server for processing. This is a serious privacy risk: JWT payloads frequently contain user IDs, email addresses, roles, session identifiers, and sometimes API keys.
⚠ Server-side decoders
- • Your token transmitted over the internet
- • May be logged in server logs
- • Exposed to third-party analytics
- • No control over data retention
✅ Base64Fix.ai
- • All decoding runs in your browser
- • Zero network requests for decode
- • No server logs of your tokens
- • AI audit only sees decoded text
Common JWT Claims Explained
subSubject — typically the user IDissIssuer — who created the tokenaudAudience — intended recipient(s)expExpiration time (Unix timestamp)iatIssued at time (Unix timestamp)nbfNot before — token invalid until this timejtiJWT ID — unique identifier for this tokenDecode Your JWT — Private & Free
Client-side only. No account. AI security audit included.
Open Base64Fix.ai →