www.mongodb.com/
MongoDB
MongoDB is free. A document database that stores records as JSON-like documents instead of table rows.
What is MongoDB?
MongoDB is free. MongoDB keeps each record as a flexible document, so you can add a field without a migration. Atlas is the hosted version and has a free tier to start. Community Server is free to run yourself.
MongoDB is a tool in the Databases category of a tech stack.
Level
Key Features
JSON-like documentsFlexible schemaAtlas free tier
MongoDB Pros & Cons
Pros of MongoDB
Add fields without a migration
Documents map cleanly to JavaScript objects
Free Atlas tier to start
Cons of MongoDB
Joins and reports are harder than in SQL
Without a schema, data drifts out of shape
Atlas jumps in price past the free and Flex tiers