What does it do?
PyJWT creates and reads JSON Web Tokens, compact, signed pieces of text that prove who you are without a website needing to check a password database on every single click. It’s similar to the wristband a concert venue gives you at the entrance: once you’ve shown your ticket, the wristband proves you belong for the rest of the night without security re-checking your ticket every time. A server creates one of these tokens after you log in, and PyJWT handles generating that token securely and later verifying that a token presented back to it is genuine and hasn’t been tampered with. The token itself can carry small amounts of information, like your user ID or when it expires.
See it in action
This creates a signed digital token containing a user’s ID, then reads that same token back and confirms it is genuine and hasn’t been tampered with.
import jwt
token = jwt.encode({"user_id": 42}, "your_secret_key_here", algorithm="HS256")
print(token)
decoded = jwt.decode(token, "your_secret_key_here", algorithms=["HS256"])
print(decoded)Why would a non-developer care?
This is a big part of how staying logged in to a website works behind the scenes without your password being checked over and over, and how different services can trust that you are who you claim to be. It’s foundational plumbing behind the login experience of an enormous share of modern apps and websites.
Real-world examples
JSON Web Tokens are an open standard used across the entire tech industry, not just Python, and PyJWT is one of the most widely used Python implementations of it, appearing in countless login systems, mobile app backends, and API authentication schemes. Any time you’ve stayed logged into a site across multiple page loads without re-entering your password, a token much like the ones PyJWT generates was likely doing the work.
Who uses it
Backend developers building login systems and APIs that need to verify a user’s identity across multiple requests without repeatedly checking a password.
How it compares to alternatives
It overlaps with python-jose, another Python JWT implementation, though PyJWT is generally considered more focused and widely adopted specifically for JWTs, while python-jose covers a broader set of related cryptographic standards under the JOSE umbrella.