Pick the engine and give the host, port (the engine's default otherwise), credentials and database (a number for Redis). Stamon connects and runs SELECT 1, or PING for Redis.

EngineQueryTLS
PostgreSQLSELECT 1Require TLS available; otherwise used when the server offers it
MySQL / MariaDBSELECT 1Require TLS available; otherwise used when the server offers it
RedisPINGNot supported yet

Use a read-only account. The password is hidden from the API once saved; it shows as ********.