MongoDB is not free, but is open technology. It can be installed and set-up using the MongoDB toolsets, but can be setup to scale superfast using the serverless version of it online.

MongoDB is a document database designed for ease of application development and scaling. A record in MongoDB is a document, which is a data structure composed of field and value pairs. MongoDB documents are similar to JSON objects. The values of fields may include other documents, arrays, and arrays of documents.

The advantages of using documents are:

  • Documents correspond to native data types in many programming languages.
  • Embedded documents and arrays reduce need for expensive joins.
  • Dynamic schema supports fluent polymorphism.

For more information about MongoDB Documentation : https://www.mongodb.com/docs/manual/

For more information about MongoDB on GitHub : https://github.com/mongodb/mongo

For more information on the pricing models for MongoDB : https://www.mongodb.com/pricing