But if you need a true $0 document database for years (not months), look at:
"ClusterIdentifier": "my-app-db", "EngineVersion": "4.0", "Tier": "FREE", // New enum value "MasterUsername": "admin", "MasterUserPassword": "********" documentdb free tier
Even within the free tier hours, if you launch a cluster with a primary + replica, you’ll burn 2×750 hours and exceed free limits in 15 days. But if you need a true $0 document