Release of FerretDB 2.0: An Open-Source MongoDB Alternative Built on PostgreSQL with Enhanced Performance and Compatibility

On March 5, 2025, the open-source project FerretDB 2.0 was officially released. This project provides an implementation of the proprietary document-oriented database MongoDB using a software stack based on PostgreSQL, allowing it to function without changes to application code. The source code is written in Go and is available on GitHub under the Apache 2.0 license. The FerretDB team has marked version 2.0 as ready for production deployment.

According to OpenNET, the primary audience for FerretDB consists of MongoDB users who are looking for a fully open-source software solution.

FerretDB supports a subset of MongoDB’s features that are commonly used in standard applications. The need for adopting FerretDB may arise due to MongoDB’s shift to a non-free SSPL license, which is derived from the AGPLv3 license but is not considered open-source because it contains discriminatory requirements regarding the licensing of not just the application code but also the source code of all components involved in providing cloud services.

MongoDB occupies a niche between fast, scalable key-value systems and relational database management systems, which are functional and user-friendly for query construction.

The MongoDB project supports document storage in a JSON-like format, offers a flexible query language, can create indexes for various stored attributes, effectively handles large binary objects, provides operation logging for data modifications, works with the Map/Reduce paradigm, and supports replication and fault-tolerant configurations.

A significant change in FerretDB 2.0 is the transition to using DocumentDB, an open-source extension to PostgreSQL developed by Microsoft that enables storage of data in the MongoDB-compatible BSON (Binary JSON) format. Initially, FerretDB focused on translating MongoDB requests into SQL queries for PostgreSQL. The switch to DocumentDB has resulted in over a 20-fold increase in performance for certain types of workloads. Other enhancements in FerretDB 2.0 include improved compatibility with MongoDB, the addition of replication capabilities, and support for vector search.