One thing I need you to understand first: you have to provide the database and the queries. Almost all of the tools in this post, except the last one, are designed to help you run queries, but they don’t include the queries. The whole idea with load testing is that you’re trying to mimic your own workloads. If you’re just trying to test a server with generic workloads, start with my post, “How to Check Performance on a New SQL Server.”
Click through for a list of tools. I’d also throw in Pigdog from Mark Wilkinson (one of my co-workers). This helped replicate a few issues in SQL Server 2017 around tempdb performance.