Build a JWT Library
Implement JWT (JSON Web Tokens) end-to-end: base64url encoding, signing with HS256/RS256, claim validation, key rotation via kid, and defenses against the well-known JWT attacks (alg=none, key confusion, weak secrets). Used by every modern auth system.
intermediate14 lessons5 chapters14 graded exercisesPython
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What you’ll have built
Chapter by chapter. Every step is a graded exercise.
- JWT Anatomy
- Signing & Verification
- Claims & Validation
- Production Concerns
- Security & Operations
Starts in Python — solve in the language you choose in the editor, same tests either way.
Curriculum
5 chapters, 14 lessons. Each lesson is a short read, one graded exercise, and a quiz.
- 1JWT Structure: header.payload.signatureRead · exercise · quiz
- 2Header & PayloadRead · exercise · quiz
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