PgBouncer

PgBouncer is a lightweight connection pooler for PostgreSQL, originally developed by Marko Kreen in 2007 and now maintained by EnterpriseDB. It addresses PostgreSQL scalability: each connection consumes 10MB+ of server memory, so hundreds of connections can exhaust resources. PgBouncer maintains a pool of persistent server connections and multiplexes many client connections over fewer server connections, enabling PostgreSQL to handle tens of thousands of clients. It supports three pooling modes: session pooling (server connection assigned for the session duration), transaction pooling (assigned only for a transaction, most efficient for web apps), and statement pooling (single statement only). Features include authentication via trust, password, MD5, SCRAM-SHA-256, and TLS certificates, configurable connection limits, query and idle timeout management, per-database and per-user configuration, admin console for monitoring, and SHOW commands for pool statistics. As of 2026, it has over 3,300 stars.