supertokens / supertokens-core

Open source alternative to Auth0 / Firebase Auth / AWS Cognito

ch4mpy / spring-addons

OAuth2 / OIDC for Spring backends of SPAs and mobile apps: the Spring Security beans the official starters leave to you (authorities, CORS, 2xx/401 for fetch, CSRF cookie, validated redirects, logout, one refresh flow at a time), as properties.

sashyo / minidauth

Mini decentralised auth. Gives an existing auth system a key nobody holds, with governance over who can decrypt.