What does MongoDB do?

MongoDB is a highly popular unstructured, NoSQL document database for powering your applications.

databases

Last updated: July 4, 2025

(MongoDB paid me to write this post. But I was going to write it anyway.)

The TL;DR

MongoDB is a highly popular document database (i.e. NoSQL) for powering your applications.

Every app (give or take a few) is powered by a production database
These days, you can choose between something structured (SQL) or unstructured (NoSQL)
Document databases are schemaless – you just throw data in, and worry about it later
MongoDB provides an ecosystem around its document DB – managed services, an IDE, analytics, and search (among other things)

MongoDB is one of the OGs of what I consider the modern tech ecosystem (IPOd back in 2017), and powers apps at over 54,500 customers. But they're not a stodgy shop – their cloud product (Atlas) has been growing like a weed recently [1] From MongoDB's most recent 10-K filing: During the year ended January 31, 2025, MongoDB Atlas revenue represented 70% of our total revenue, as compared to 66% in the prior year, reflecting the continued growth of MongoDB Atlas since its introduction in June 2016., and their website actually (gasp) explains what the product does. So let's dive in and see what they're all about.

Terms Mentioned

Open Source

JavaScript

SQL

Client

Production database

NoSQL

Schema

Server

Cloud

Production

Data lake

Terminal

Deploy

Database

Vector Database

Query

Relational database

Companies Mentioned

AWS

$AMZN

MongoDB

$MDB

The core MongoDB product: NoSQL database

Unlike SQL databases which are all about structure and rigor, NoSQL is exactly what you think it is – unstructured. Instead of rigidly defining what your data looks like before storing it, you just kind of throw it in there and worry about it later. Querying it is more difficult, but it’s a lot easier to scale horizontally to multiple servers. Neither is better or worse, it just depends on the kind of app you’re building.

If you are going with NoSQL, MongoDB offers probably the best version of it that you don’t need to set up yourself. The MongoDB product is a fully managed, high scale NoSQL (or document, as they call it) database. And like other managed databases, it comes with built in observability, backups, easy to use client libraries, etc.

A refresher – what’s NoSQL?

Although their marketing has moved away from the NoSQL moniker in recent years, the key to understanding MongoDB – and why they had such a major impact on the ecosystem – is to understand NoSQL.