Question 1

What is FerretDB?

Accepted Answer

FerretDB is an open-source database that speaks the MongoDB wire protocol — so MongoDB drivers, mongosh, and application code connect to it just like MongoDB — while storing data in PostgreSQL underneath.

Question 2

Why would I use it instead of MongoDB?

Accepted Answer

Mainly licensing. MongoDB moved to the SSPL, which isn't OSI-approved open source and imposes conditions many companies and cloud providers can't accept. FerretDB gives you the MongoDB API and drivers under a truly open Apache 2.

Question 3

Which port does it use?

Accepted Answer

This deployment listens on host port 27018, deliberately not MongoDB's default 27017. That lets a real MongoDB instance and FerretDB coexist on the same host and removes any ambiguity about which you're connecting to. Point your MongoDB clients and connection strings at 27018.

Question 4

Is it fully compatible with every MongoDB feature?

Accepted Answer

It implements a large subset of the MongoDB API — enough for many applications — but not the entire feature set. Before migrating, verify that the specific operators, aggregation stages, and operations your workload relies on are supported.

Question 5

Do I back it up like MongoDB or PostgreSQL?

Accepted Answer

Like PostgreSQL, because that's where the data actually lives. Back up the ./db volume, ideally with standard PostgreSQL tools such as pg_dump for a consistent snapshot, and store the generated PostgreSQL password alongside your backups.

Port	Purpose
27018	FerretDB MongoDB-compatible endpoint (mapped from container port 27017)
5432	PostgreSQL with DocumentDB — internal to the Docker network, not exposed

🗄️ Setup FerretDB — MongoDB-Compatible on PostgreSQL

📦 Resources & Setup Scripts

Quick Install:

Tutorial Steps

1 Download the Script

2 Make it Executable

3 Run the Installer

4 Connect with a MongoDB Client

Ports Used

Overview

Why Use It

When You Need It

Who Should Use It

Real Use Cases

Main Features

How to Use After Installation

Security Best Practices

Ports and Firewall Notes

Backup and Maintenance

Common Mistakes

Troubleshooting

Alternatives

When Not to Use It

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Frequently Asked Questions