PostgreSQL vs FerretDB
Both are alternatives to MongoDB Atlas. Here's how they stack up — verified facts, no spin.
Also searched as FerretDB vs PostgreSQL — same comparison, one verdict.
PostgreSQL
TOP PICKThe default answer, and JSONB means you may not need a document store.
Postgres is the most capable open database in general use and the one most teams should reach for first. The detail that matters on this page: JSONB gives you schemaless document storage with indexing and rich querying inside a relational database, so you can hold documents where they suit and use joins, transactions and constraints everywhere else. Add pgvector for embeddings and full-text search built in, and a large share of MongoDB deployments turn out to be Postgres deployments that took a detour. PostgreSQL Licence — permissive, foundation-governed, and not going to change.
FerretDB
MongoDB's wire protocol, speaking to Postgres underneath.
FerretDB implements the MongoDB wire protocol on top of Postgres, so an existing application keeps its drivers, its queries and its code while the data lives in an open relational database under a licence nobody will change. Apache-2.0, around 11k stars. It is the most surgical exit in this comparison: for the common case of a team using MongoDB as a straightforward document store, it is close to a drop-in. Compatibility is good rather than total — the exotic aggregation stages and MongoDB-specific features are where it stops.
Side by side
| PostgreSQL | FerretDB | |
|---|---|---|
| Sovereignty Score | 98 | 95 |
| Open source | Yes | Yes |
| Self-hostable | Yes | Yes |
| Local-first | Yes | Yes |
| License | PostgreSQL License (permissive) | Apache-2.0 |
| Pricing | Free and open source. Managed options exist from every cloud, usually cheaper than Atlas. | Free and open source. You run it alongside your own Postgres. |
PostgreSQL is Macrostack's recommended MongoDB Atlas alternative, so it's our pick here.
PostgreSQL
Strengths
- +JSONB covers most document workloads without giving up relational features
- +pgvector and full-text search built in — no second database
- +Governance by a foundation; the licence will not be changed under you
- +Every cloud offers a managed version, so you are never captive to one
Trade-offs
- −Migrating from MongoDB means rewriting queries, not just moving data
- −Horizontal sharding is harder than MongoDB's
- −Genuinely document-shaped workloads at huge scale fit MongoDB better
- −Operating it yourself is still real work
FerretDB
Strengths
- +Existing MongoDB drivers and queries keep working — minimal code change
- +Apache-2.0, with data resting in Postgres
- +Sidesteps the SSPL question entirely
- +Lets you consolidate onto one database engine
Trade-offs
- −Compatibility is good but not complete — test your aggregations
- −Extra layer between application and storage
- −Younger project with a smaller community
- −Not faster than MongoDB; this is about licence and consolidation
More MongoDB Atlas head-to-heads
Related alternative guides
Facts verified 2026-08-07. Licenses and pricing change — spotted something out of date? That's a correction we want.