Cemal Kilic enhanced the supabase/cli repository by implementing secure API authentication features focused on asymmetric signing and safe JWKS exposure. He introduced support for asymmetric signed API keys using JWKs, with a fallback to symmetric signing, and developed helpers for JWK conversion and JWT generation to streamline key material handling. By refining JWKS exposure to publish only public keys and restricting key operations to verification, he reduced the risk of private key leakage. Working primarily in Go, Cemal applied his expertise in API security, backend development, and cryptography to deliver a robust solution that strengthens authentication workflows and integration safety.