MongoDB

MongoDB is a document database maintained by MongoDB Inc. that stores flexible, JSON-like documents instead of rigid rows and columns. It's the sixth most-used database in developer surveys, at roughly 24% usage share. It's especially popular in JavaScript-stack apps — it's the "M" in MERN — because its schema can evolve without formal migrations, which speeds up early-stage development.

Example

The Mongo shell inserts and queries JSON-like documents directly — no table schema to define up front.

db.users.insertOne({
  name: "Ava Chen",
  age: 27,
  tags: ["admin", "beta_tester"]
});

// find users over 21, sorted by name
db.users.find({ age: { $gt: 21 } })
  .sort({ name: 1 });

Getting started

Run a local instance with Docker, then connect with the mongosh shell.

# Docker: run a local MongoDB instance
docker run --name mongo -p 27017:27017 -d mongo:7

# connect with the mongosh shell
mongosh "mongodb://localhost:27017"