Appwrite vs. Keycloak
Appwrite
appwrite.io/Appwrite is an open-source platform for building scalable applications. It comes with authentication, databases, storage, and functions. It's basically a complete development platform. They have an extremely generous free plan with 75,000 MAUs free of charge and their Pro plan is only $15/month. Appwrite offers email and password login, phone auth, magic links, email OTP, anonymous login, JWT login, SSR login, custom tokens, and two-factor authentication.
Keycloak
www.keycloak.org/Keycloak is an open source identity and access management solution. It supports Keycloak single-sign-on and OpenID Connect or SAML 2.0 Identity Providers (Google, Facebook, GitHub etc).