The MERN stack (MongoDB, Express, React, Node.js) has become one of the most popular choices for modern web development due to its flexibility, scalability, and the ease with which the technologies work together. MongoDB is the default database for many MERN stack developers, primarily because it is a NoSQL database and integrates seamlessly with Node.js. However, MongoDB isn’t the only option available for building a robust, scalable backend. Depending on your project’s requirements, you might prefer to use a different database.

In this article, we will explore the best databases to use with the MERN stack, apart from MongoDB. Each database has its unique strengths and can be an excellent choice for specific use cases, from relational data management to high scalability and real-time applications. Whether you’re building a large-scale enterprise application or a small personal project, there’s a database that will suit your needs.

1. PostgreSQL: A Powerful Relational Database

PostgreSQL is an open-source, object-relational database system that is widely regarded for its stability, extensibility, and support for advanced SQL features. If your application requires complex queries, a high level of data integrity, or sophisticated transaction handling, PostgreSQL is an excellent choice. It is fully ACID-compliant, which ensures that transactions are processed reliably, even in the event of a system crash.

PostgreSQL is not only known for its SQL features but also its ability to handle JSON data types through its JSONB feature. This gives developers the flexibility to combine the structure of SQL with the unstructured nature of NoSQL, making it ideal for hybrid applications. If your project involves extensive data relationships, PostgreSQL’s support for foreign keys, joins, and transactions ensures a solid foundation for building complex, data-driven applications.

When integrating PostgreSQL with a MERN stack, you can use Node.js libraries such as pg or ORM frameworks like Sequelize or TypeORM for a more structured approach. These tools allow you to interact with PostgreSQL using JavaScript, making it easy to manage the database and implement queries directly within your Node.js backend.

2. MySQL: A Highly Efficient Relational Database

MySQL is another widely used relational database that has been a staple in the development world for decades. Known for its speed and reliability, MySQL is a strong contender for any application that requires structured data storage and SQL querying. It is particularly useful for applications that handle a large number of read and write operations, such as e-commerce platforms, content management systems, and business applications.

One of MySQL’s standout features is its performance, especially when it comes to handling read-heavy applications. For projects that involve a large number of concurrent users or need fast access to data, MySQL provides excellent scalability options through indexing and query optimization techniques.

MySQL also supports replication, which means you can set up master-slave configurations for load balancing and increased reliability. This makes it an excellent choice for building high-traffic applications. If your project relies on relational data and complex queries, MySQL is a solid option for your MERN stack backend.

Integrating MySQL with MERN can be done using libraries like mysql2 or using ORM tools like Sequelize or TypeORM, which allow developers to interact with MySQL using JavaScript and simplify the management of data relationships.

3. SQLite: Lightweight and Serverless

SQLite is a lightweight, file-based database that doesn’t require a dedicated server. It’s an excellent choice for small-scale applications, mobile apps, or for use in development and testing environments. While SQLite isn’t suitable for applications that need to scale horizontally or handle heavy concurrent traffic, it is ideal for situations where simplicity and ease of use are paramount.

SQLite is embedded directly into the application, making it easy to set up and use without the overhead of managing a separate database server. It is commonly used in mobile applications or small web apps that don’t require a full-fledged database management system.

When working with SQLite in the MERN stack, you can use the sqlite3 package in Node.js, or you can opt for an ORM like Sequelize, which allows you to define models and perform database operations seamlessly within your application.

4. Cassandra: A NoSQL Database for High Scalability

Cassandra is a distributed NoSQL database designed to handle huge amounts of data across many servers. It is built to provide high availability, scalability, and fault tolerance, making it ideal for applications that need to handle large volumes of data and ensure uptime even during network failures or server outages. If your application requires a highly scalable, fault-tolerant solution, Cassandra might be the right choice.

Unlike MongoDB, which stores documents, Cassandra uses a column-family store to organize data. This makes it particularly well-suited for time-series data, real-time analytics, or applications that require fast writes and large data sets. Cassandra is used by companies like Netflix, Instagram, and Spotify for managing their massive datasets at scale.

Integrating Cassandra with your MERN stack can be done using the cassandra-driver for Node.js. This driver allows you to connect to Cassandra, perform queries, and manage data within your backend.

5. Redis: A High-Performance In-Memory Store

Redis is an in-memory data store that can be used as a cache, session store, or for real-time data processing. While Redis isn’t typically used as a primary database for storing persistent data, it’s highly effective for scenarios where low-latency access to data is critical. Redis excels at handling high-throughput workloads and can store a wide range of data types, including strings, hashes, lists, sets, and sorted sets.

Redis is commonly used in applications that require fast data retrieval, such as caching frequently accessed data, managing user sessions, or handling real-time data for messaging or notification systems. It can also be used to store application state or for pub/sub messaging between services.

To integrate Redis with MERN, you can use the ioredis or redis Node.js clients. These libraries make it easy to connect Redis to your Node.js backend and implement caching, sessions, and real-time features.

6. Firebase Firestore: Real-Time NoSQL Database

Firebase Firestore is a cloud-based NoSQL database developed by Google. It provides real-time data synchronization across multiple devices and offline data persistence, which makes it ideal for mobile apps or applications that require real-time updates. Firestore is part of the broader Firebase ecosystem, which includes authentication, hosting, and cloud functions, making it a powerful tool for building full-stack applications.

Firestore is particularly useful for applications that require automatic syncing of data across devices, such as collaborative apps, chat applications, or apps with live updates. The real-time features in Firestore allow for seamless user experiences, where data updates reflect instantly without needing to refresh the app.

Integration with MERN is straightforward, as Firebase provides an official SDK that can be easily used in your Node.js backend. Firebase also offers SDKs for React, which makes it simple to integrate Firestore into the front end of your MERN stack application.

7. CouchDB: A Document-Based NoSQL Database

CouchDB is another document-based NoSQL database that uses JSON for data storage. CouchDB is designed with replication and synchronization in mind, making it an excellent choice for apps that need offline capabilities or peer-to-peer data syncing. It is known for its simplicity, reliability, and ease of use. CouchDB supports MapReduce for views, which can be used to aggregate data.

Similar to MongoDB, CouchDB stores JSON documents but offers a unique set of features for working with distributed data. If your application needs easy replication across multiple nodes or offline data access, CouchDB might be an ideal fit.

To integrate CouchDB into your MERN stack, you can use libraries like nano or pouchdb, which make it easy to interact with the database from your Node.js application.

8. Neo4j: A Graph Database for Connected Data

Neo4j is a graph database that is specifically designed to store and query highly connected data. It’s an ideal choice for applications that need to work with complex relationships, such as social networks, recommendation engines, and fraud detection systems. Instead of using rows and columns, Neo4j stores data as nodes and edges, which are linked to each other through relationships.

If your MERN stack application requires handling of highly interconnected data, such as modeling relationships between users, products, and transactions, Neo4j is a powerful solution. Neo4j’s Cypher query language allows you to query graph data intuitively and efficiently, making it a great choice for applications that need to explore complex relationships between entities.

Neo4j can be integrated with MERN using the official neo4j-driver for Node.js, which allows you to query the graph database directly from your backend and incorporate it into your application.