The top 5 MongoDB-compatible alternatives to MongoDB include: FerretDB, DocumentDB, CosmosDB, GaussDB(for Mongo), and MariaDB MaxScale.
MongoDB has profoundly impacted many developers and companies with its powerful and developer-friendly NoSQL database that's resulted in a 45% market share among NoSQL databases in the world.
But that's not the only reason for its popularity. MongoDB is a schemaless document-based database that allows you to build data models with increased flexibility and scalability. Through its cloud service offering, MongoDB Atlas, it enables users to run, deploy, scale, and manage their instances in the cloud.
For many years, MongoDB's robust wire protocols, SDKs, tools, and previously open-source license meant it was the go-to choice for people looking for a reliable, open, and developer-friendly database for their applications. Sadly, the switch to a proprietary license has forced many to look for open source MongoDB alternatives that would serve their unique needs.
Open source vs. proprietary database software
Unlike proprietary databases, open source database solutions give you the freedom to innovate and extend the functionalities of the database. This enables a greater level of innovation, allowing a wider pool of developers to contribute to its development.
Aside from that, users can easily avoid vendor lock-in, manage their own data, and effortlessly host or migrate to any platform of choice.
Due to the attraction and many benefits of open source software, several companies still attempt to hide under the umbrella of "open source software" even when all indications suggest otherwise. Case in point: MongoDB.
If you conduct a simple search to see if it's open source, you'll likely arrive at an article that describes it as one. But what does it mean to be truly open source, and what benefits do they have over proprietary databases?
An open source software is licensed under Apache License 2.0, or other similar licenses approved by the Open Source Initiative (OSI) that follow the principles of open source to be freely available to modify, use, deploy, and manage, and most importantly.
Yet, in the last few years, there have been some redefinitions and untruths on what open source actually means.
The biggest culprits and prime examples among them are MongoDB's Server Side Public License (SSPL) and Elastic's source-available license, Elastic license. None of these licenses have been endorsed by the Open Source Initiative, generally considered the official arbiters in the open source community.
While several euphemisms are used to describe these licenses as either free or open, they are not. They come with restrictions that go against the principles of OSS. For instance, under a proprietary license like SSPL, you can't run MongoDB as a service unless you release all the support code and underlying infrastructure – or otherwise, pay for the enterprise version – MongoDB Atlas.
These proprietary database solutions can be pretty expensive and easily lead to vendor lock-in, especially for users who still consider them to be open source.
But remember: If they can change the license once, what's to stop them from doing it again?
And in such cases, what other MongoDB-compatible alternatives can you consider, especially if you need to migrate away from MongoDB?
Top 5 alternatives to MongoDB
Here are the most MongoDB-compatible databases and alternatives that you can consider today:
FerretDB is the de-facto open source alternative to MongoDB. It converts MongoDB wire protocols to SQL, with the backend on PostgreSQL.
FerretDB provides users with the same MongoDB syntax and commands that developers are accustomed to when using MongoDB. That means you get a document-based database's ease of use and flexibility.
But that's not where the similarities end. When combined with a database as a service platform like Tigris as the backend, FerretDB can provide cloud-based functionality, giving you total control of your infrastructure while avoiding vendor lock-in associated with MongoDB Atlas.
However, it's important to note that FerretDB is still under development. With the recent release of its first developer preview (FerretDB v0.9.0), users are welcome to try it out and explore the various features available.
DocumentDB is Amazon's answer to a MongoDB alternative. It is a proprietary NoSQL database service that's compatible with MongoDB and supports real-time scalability and unlimited storage. It lets you take advantage of existing MongoDB drivers and tools to run, manage, and scale workloads.
Amazon DocumentDB has a decoupled architecture where storage and compute run independently, making it easier to scale dynamic workloads. With its deep integration with AWS services, DocumentDB offers compelling reasons as the ideal alternative for MongoDB. However, since DocumentDB is a proprietary database, vendor lock-in still remains an underlying problem.
3. Cosmos DB for MongoDB
The Azure Cosmos DB for MongoDB offers a MongoDB-like platform for Azure users. It uses the MongoDB wire protocols, enabling compatibility with MongoDB protocols, drivers, and tools. Users can also use its instant scalability features with little or no warmup time.
Cosmos DB offers a fully managed database on Azure, enabling you to manage all your infrastructure on your own. Since it can only run on Azure, it raises the same vendor lock-in concerns that stop you from deploying in multiple cloud environments, the same as MongoDB.
4. MariaDB MaxScale - NoSQL Protocol Module
MaxScale is a database proxy that allows applications to access MariaDB databases while enjoying the benefits of a decoupled architecture. With MaxScale's NoSQL Protocol module, you have another viable alternative to MongoDB.
MaxScale NoSQL protocol module is a communication protocol between MariaDB and MongoDB, which enables the use of a MariaDB server or cluster as the backend for an application that uses a MongoDB client library.
Users can interact with MariaDB databases using NoSQL-style commands, which are then converted into SQL and executed on the MariaDB backend. The responses from MariaDB are then transformed into the format required by the MongoDB client library and application.
The MariaDB NoSQL protocol module is suitable for users that require relational database support, scalability, and integration with existing MariaDB infrastructure. Note that MaxScale is published under a proprietary licence (BSL), meaning you're still faced with similar concerns of vendor lock-in.
5. GaussDB(for Mongo)
GaussDB(for Mongo) is a proprietary cloud-native database that's compatible with MongoDB. Similar to DocumentDB, it offers decoupled storage and compute, enabling seamless and flexible scaling.
GaussDB is especially good for gaming applications that require enterprise-class performance, high flexibility and storage capacity, and a friendly UI. The ease of adding compute nodes makes it perfect for online gaming scenarios with high-concurrency levels.
Notable Mention: ToroDB
ToroDB is not a part of this list due to the limited activity on the project in recent years; however, it's another MongoDB alternative that's worthy of mention.
ToroDB is an open source database service built to read and convert MongoDB NoSQL to SQL. With PostgreSQL as the storage layer, ToroDB doesn't use jsonb; Instead, it uses a relational approach to store data. ToroDB also implements the MongoDB protocol, making it compatible with most MongoDB applications.
Despite ToroDB's potential as a viable MongoDB alternative, one big red flag is the absence of consistent updates or improvements on the database project for a while now, making it an unlikely choice for would-be users. In fact, there hasn't been any activity on the project since 2019. Nevertheless, the project is still available on GitHub, and users can happily experiment with it.
Choosing the MongoDB alternative for your app
Before choosing an alternative to MongoDB, it's important to take several factors into consideration, including ease of use, flexibility, vendor independence, scalability, cost, and maintenance.
For users with high availability and storage demands, little concern for vendor lock-in, and the budget to accommodate it, choosing a proprietary solution between DocumentDB, CosmosDB, or GaussDB would be the best option.
For developers or organizations that would love to be part of a growing community of open source enthusiasts with the freedom to run, manage, and host their database as they wish, FerretDB would be an ideal choice. An open source database service like FerretDB offers complete vendor independence, offering MongoDB compatibility that helps you to leave MongoDB without rewriting your application.