What is better for app development, PostgreSQL or MongoDB?

It depends on the app, but for most app development, PostgreSQL is the better default choice.

PostgreSQL is better when:

• You have relational data: users, orders, comments, payments, etc.
• You need strong consistency and reliable transactions
• You want powerful querying with joins, indexes, constraints
• Your data structure is likely to evolve, but still benefits from a schema
• You want one database that can also handle JSON well when needed

MongoDB is better when:

• Your data is very flexible or document-shaped
• You want to store nested objects without lots of joins
• Your schema changes often and you prefer quick iteration
• You’re building something like a content app, catalog, logging, or event-heavy system

In practice

For many typical web/mobile apps:

• PostgreSQL is often the safer and more scalable long-term choice.
• MongoDB can be great for specific use cases, but “schema-less” is not automatically easier once the app grows.

Simple rule of thumb

• Choose PostgreSQL if you’re unsure.
• Choose MongoDB if your data is naturally document-based and you rarely need relational joins.

If you want, I can also give you a decision table based on your app type (SaaS, social app, e-commerce, analytics, etc.).