Apache Kafka vs SQL Server

Apache Kafka and SQL Server are free.

Apache Kafka

Free

A log that services publish events to, and other services read later.

Pros of Apache Kafka

Producers do not wait on every downstream service
You can replay events after a bug
It holds up once you actually have a stream of events

Cons of Apache Kafka

Running a cluster is a lot for one app
A database is the simpler choice until you need a stream

SQL Server

Free

Microsoft’s relational database. The usual pair with C# and Azure.

Pros of SQL Server

Natural pair with C#
Strong Azure tooling
Express is free to start

Cons of SQL Server

Paid editions get expensive
Less common outside Microsoft shops