What does it do?
Authlib implements OAuth and OpenID Connect, the technical standards behind letting you log into one website using your Google, Facebook, or GitHub account instead of creating a new password. It functions like a professional interpreter fluent in a very specific, precise negotiation protocol between three parties: you, the website you’re visiting, and the service you’re logging in with. Authlib can play any of those roles in Python code, letting a developer build a service that either lets users log in via another provider, or lets a service become the provider that other apps log in through. Getting these handshakes right by hand is notoriously fiddly and easy to get subtly, dangerously wrong.
See it in action
This sets up a connection using an app’s registered ID and secret, then generates the special web address a user would visit to log in and approve access.
from authlib.integrations.requests_client import OAuth2Session
client = OAuth2Session(
client_id="your_client_id_here",
client_secret="your_client_secret_here",
)
uri, state = client.create_authorization_url("https://example.com/oauth/authorize")
print(uri)Why would a non-developer care?
The convenience of not needing yet another password to remember, and the light reassurance that a big company is vouching for who you are, depends entirely on this kind of protocol being implemented correctly. A mistake in this exact area of software has historically led to real account takeover vulnerabilities across the industry.
Real-world examples
OAuth and OpenID Connect are the open standards underlying sign-in buttons across nearly the entire internet, and Authlib is one of the more complete, actively maintained Python implementations covering both the client and server side of that exchange. Building this from scratch is discouraged industry-wide precisely because subtle mistakes in the protocol have led to real security breaches.
Who uses it
Developers building either the log-in-with button experience for their app, or the reverse, a service that wants to let other applications authenticate through it.
How it compares to alternatives
It overlaps with the narrower oauthlib, which implements just the OAuth signing logic, while Authlib bundles OAuth, OpenID Connect, and JWT support together into a more complete package aimed at building full authentication systems.