MongoDB Alternative: Why FerretDB is the Future of Open-Source Document Databases

Quick Answer

FerretDB is the leading open-source alternative to MongoDB. It provides MongoDB wire protocol compatibility while storing data in PostgreSQL, ensuring true open-source freedom without vendor lock-in. Developers choose FerretDB because it combines MongoDB’s ease of use with PostgreSQL’s reliability, making it the future of open-source document databases.

Why Developers Are Looking for a MongoDB Alternative

MongoDB started as the most popular NoSQL database, but in 2018 it switched to the Server Side Public License (SSPL). While technically “source available,” SSPL is not recognized as an open-source license by the OSI.

This change raised concerns among:

• Startups worried about cloud vendor lock-in
• Enterprises seeking license compliance
• Open-source advocates who want freedom to build without restrictions

As a result, demand for a true open-source MongoDB alternative has been growing. That’s where FerretDB steps in.

What is FerretDB?

FerretDB is a document database designed as a drop-in MongoDB alternative. It speaks the MongoDB wire protocol but translates commands into PostgreSQL queries under the hood.

This means:

• Your existing MongoDB drivers work with FerretDB
• CRUD operations behave as expected
• You get the reliability, scalability, and ecosystem of PostgreSQL

👉 You can even host PostgreSQL with OctaByte and run FerretDB on top of it for a fully managed, open-source stack.

Key Benefits of FerretDB Over MongoDB

1. True Open-Source Freedom

Unlike MongoDB’s SSPL, FerretDB is licensed under Apache 2.0, ensuring no vendor lock-in or usage restrictions.

2. MongoDB Compatibility

FerretDB supports:

• CRUD operations
• Indexes
• Queries and filters
• Compatibility with MongoDB drivers and tools

3. Powered by PostgreSQL

By using PostgreSQL as its backend, FerretDB inherits:

• ACID compliance
• Advanced indexing and extensions
• Proven scalability and reliability

4. Easy Migration Path

If you’re already using MongoDB, you can migrate to FerretDB with minimal code changes. For developers frustrated by MongoDB’s license but still wanting the same API, FerretDB is a perfect fit.

FerretDB vs MongoDB: A Quick Comparison

Use Cases for FerretDB

• Startups → avoid MongoDB licensing risks while staying API-compatible
• Enterprises → compliance-friendly open-source database
• Developers → learning document databases without cloud lock-in
• Hybrid Projects → combine PostgreSQL relational power with MongoDB-style NoSQL

FerretDB’s hybrid nature makes it appealing to teams that want the best of both worlds.

FerretDB in the Open-Source Database Ecosystem

FerretDB isn’t just an isolated project — it’s part of the new wave of open-source databases challenging closed licenses.

You can explore more options in our Ultimate Guide to Open-Source Databases (2025), which covers relational, NoSQL, time-series, and vector databases.

Other alternatives worth considering:

• Redis and Valkey for in-memory workloads
• ScyllaDB as a Cassandra replacement
• OpenSearch as an Elasticsearch alternative

FerretDB joins these as the go-to alternative for MongoDB.

Future of FerretDB

FerretDB is actively developed with growing community support. Key areas of improvement include:

• Expanding query support
• Performance tuning on PostgreSQL
• Better integration with ORMs and cloud-native platforms

With more enterprises adopting open-source-first strategies, FerretDB is positioned to become the default open-source document database in the coming years.

Final Thoughts: Is FerretDB the Right MongoDB Alternative?

If you’re looking for a MongoDB alternative that is truly open-source, PostgreSQL-backed, and developer-friendly, FerretDB is your best option.

It offers MongoDB compatibility without the licensing headaches, making it the future of open-source document databases.

Want to try it? Check out FerretDB fully managed with OctaByte and run MongoDB workloads on open-source foundations.

FAQ: MongoDB Alternative & FerretDB

❓ Is FerretDB really a drop-in replacement for MongoDB?

Yes, FerretDB supports the MongoDB wire protocol, meaning your existing drivers and tools work with minimal changes.

❓ Why is MongoDB no longer considered fully open-source?

Because MongoDB adopted the SSPL license, which the OSI does not approve as open source. This restricts how it can be used, especially by cloud providers.

❓ Can I migrate from MongoDB to FerretDB easily?

Most workloads migrate smoothly since FerretDB is designed for compatibility. Some advanced MongoDB features may not be fully supported yet, but development is ongoing.

❓ Why use PostgreSQL as the backend for FerretDB?

PostgreSQL brings decades of reliability, ACID transactions, indexing, and extensions — making FerretDB more robust than typical NoSQL-only systems.

Want more open-source hosting insights? Don’t miss our guide: The Ultimate Guide to Open-Source Databases (2025)