JSON Web Tokens in Python
Create, sign, and verify JWTs in Python using PyJWT — with HS256 and RS256 examples.
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Tags: JWT Python PyJWT, Python JWT library, PyJWT examples
JSON Web Tokens in Python JSON Web Tokens are defined in RFC 7519 by the IETF. The signing algorithms are specified in RFC 7518 (JSON Web Algorithms). The PyJWT library documentation is the primary reference for Python JWT implementation. PyJWT is the standard Python library for creating, signing, and verifying JSON Web Tokens. This guide covers HS256 (shared secret), RS256 (RSA keypair), and ES256 (elliptic curve) with full examples. --- What is installation? PyJWT 2.x (the current major version) changed the default return type of from bytes to str — if you are upgrading from PyJWT 1.x, update code that calls on the result. What is hs256: shared secret? HS256 uses HMAC-SHA256. Both signing and verification use the same secret string or bytes. What is rs256: rsa keypair? RS256 uses…
Frequently Asked Questions
How do I use PyJWT in Python?
Install PyJWT with pip, import jwt, then call jwt.encode(payload_dict, secret, algorithm='HS256') to sign and jwt.decode(token, secret, algorithms=['HS256']) to verify. PyJWT handles Base64URL encoding, signature computation, and claim validation automatically.
How do I sign a JWT with RS256 in Python?
Install PyJWT with the cryptography extra: `pip install PyJWT[cryptography]`. Read your RSA private key file as bytes, then call `jwt.encode(payload, private_key, algorithm='RS256')`. Verifiers use the corresponding RSA public key.
How do I verify JWT expiry in Python?
PyJWT verifies the `exp` claim automatically when you call jwt.decode(). If the token is expired, it raises `jwt.ExpiredSignatureError`. Set a leeway parameter to allow for small clock skew between systems: `jwt.decode(token, key, algorithms=['HS256'], leeway=10)` allows 10 seconds of skew.
How do I decode a JWT without verification in Python?
Use `jwt.decode(token, options={'verify_signature': False})` to decode the payload without checking the signature. This is useful for debugging or when you need to read the header to determine which key to use for verification. Never use this in production authentication flows.
How do I use JWK for JWT verification?
Use the `PyJWT` library with `python-jose` or the `jwcrypto` library to fetch and parse JWKS (JSON Web Key Set) endpoints. PyJWT 2.x supports JWK directly: `from jwt.algorithms import RSAAlgorithm; public_key = RSAAlgorithm.from_jwk(json.dumps(jwk_dict))`.
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