| PostgreSQL | MongoDB | |
|---|---|---|
| Maintainer | PostgreSQL Global Development Group | MongoDB, Inc. |
| First release | 1996 | 2009 |
| License | PostgreSQL License | SSPL |
| Learning curve | Moderate, standard SQL gets you far, but the rich feature surface (indexes, JSONB, extensions, tuning) rewards deeper study. | Easy to start. Documents map naturally to application objects; data modeling discipline is what separates good deployments from painful ones. |
| Performance | Excellent transactional performance and strong analytics for its class; scales vertically very well and horizontally via read replicas or Citus. | Fast document reads and writes with horizontal sharding built into the core; multi-document transactions exist but cost more than their SQL equivalents. |
PostgreSQL should be the default for most products, strict integrity, powerful SQL and JSONB when you need document flexibility inside the same engine. MongoDB earns its place when the schema genuinely changes fast, data is naturally document-shaped, or built-in sharding across huge write volumes is a day-one requirement.