Some top database providers for various open source databases like MariaDB, PostgreSQL, MongoDB, Apache Cassandra, Redis, Elasticsearch, and Neo4j:

1. MariaDB:
   • Amazon RDS for MariaDB
   • Google Cloud SQL for MariaDB
   • Microsoft Azure Database for MariaDB
   • MariaDB via SkySQL (deploys to multiple clouds)
2. PostgreSQL:
   • Amazon RDS for PostgreSQL
   • Google Cloud SQL for PostgreSQL
   • Microsoft Azure Database for PostgreSQL
   • Aiven for PostgreSQL
   • ScaleGrid for PostgreSQL
   • Neon PostgreSQL (cool integration here and here w/ Vercel integration)
3. MongoDB:
   • MongoDB Atlas
   • Google Cloud MongoDB
4. Apache Cassandra:
   • DataStax Astra (Cassandra as a service)
   • Aiven for Apache Cassandra
   • Instaclustr for Apache Cassandra
5. Redis:
   • Redis Labs (Redis Enterprise)
6. Elasticsearch:
   • Amazon Elasticsearch Service
   • Elastic Cloud
   • Aiven for Elasticsearch
   • Bonsai Elasticsearch
7. Neo4j (Graph Database):
   • Neo4j Aura (cloud-based service)