JWT Decoder vs Base64 Encode / Decode
JWTs use Base64url encoding internally, but they are very different concepts. Base64 is an encoding scheme; JWT is an authentication token format.
JWT Decoder
JWT decoder — decode and inspect JSON Web Tokens instantly in your browser. View the decoded algorithm header, payload claims (sub, iat, exp, aud, iss), and expiration status. Flags expired tokens automatically. No signature verification — safe for debugging without exposing your secret key.
- ✓Structured format: header.payload.signature
- ✓Contains claims: iss, sub, exp, iat, etc.
- ✓Signature verifies authenticity and integrity
- ✓Used for authentication and authorization
- ✓Can be verified without a database lookup
Base64 Encode / Decode
Base64 encode or decode any text or binary data instantly in your browser. Supports standard Base64, URL-safe Base64, and padding-free variants used in JWT tokens, data URIs, HTTP Basic Auth, and email attachments. No data leaves your device.
- ✓Pure encoding — no structure or semantics
- ✓No signature or integrity checking
- ✓Trivially decodable by anyone
- ✓Used to encode arbitrary binary data
- ✓Foundation that JWTs happen to use internally
When to use each
You need authenticated, stateless tokens for user login sessions, API authorization, or inter-service communication.
You simply need to encode arbitrary data as ASCII text — no authentication, no structure, no expiry needed.