DynamoDB and MongoDB are free.
AWS key-value and document database that scales without a server to patch.
Try itNo servers to run
Scales with traffic
Fits the rest of AWS
Awkward when you need joins
Easy to get the data model wrong
Tied to AWS
A document database that stores records as JSON-like documents instead of table rows.
Try itAdd fields without a migration
Documents map cleanly to JavaScript objects
Free Atlas tier to start
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