Keycloak Alternatives (2026)

Rekey.dev

Auth, billing, and MCP for agent products

Rekey is an OAuth 2.1 authorization server designed for MCP servers, providing essential features like discovery, dynamic client registration, and PKCE. It enables developers to manage credits, usage quotas, and licenses that AI agents bill against. The toolkit includes two MCP servers and is both...

ovlt

lightweight-auth-server

> Most auth servers demand more RAM than your actual app - Keycloak at 512MB, Authentik at 735MB. OVTL is a self-hosted OAuth2 + OIDC server written in Rust that idles at ~20MB, giving you multi-tenant isolation, zero-knowledge encryption, MFA, Passkeys and social login in a single binary that runs...