Header
The first segment of a JWT, Base64URL-encoded JSON typically containing alg (algorithm) and typ (token type). Always verify alg before trusting a token.
Quick Answer
See our full JWT Glossary for related terms, or use the JWT Decoder to inspect tokens in practice.
What is Header?
The first segment of a JWT, Base64URL-encoded JSON typically containing alg (algorithm) and typ (token type). Always verify alg before trusting a token.
See It in Practice
Paste any JWT into our JWT Decoder to see related claims in action. Use the JWT Debugger for detailed analysis.
Related
Browse the full JWT Glossary or explore JWT Basics.
Header in JWT Authentication
Understanding Header helps you read RFC 7519, debug tokens, and design secure authentication. JWTs combine header, payload claims, and a cryptographic signature.
Browse related resources: JWT Decoder, JWT Validator, JWT Basics, JWT Authentication, JWT Errors, Algorithms, Glossary, and Learning Path.