This page mentions a few of the most well-known free SQL Server tools for which SQLFacts offers overlapping functionality.
Glenn Barry created a set of queries to investigate SQL Server memory usage.
The SQLFacts suite of tools provides very similar functionality with Sessions, Resources, MetricsNow, and Bufferin.
Adam Machanic created sp_WhoIsActive to investigate what SQL code is running.
The SQLFacts suite of tools provides very similar functionality with Sessions.
Brent Ozar created sp_Blitz, sp_BlitzIndex, sp_BlitzCache, and more to investigate performance issues.
The SQLFacts suite of tools provides very similar functionality with MetricsNow, IndexHistory, QueryHistory, and others.
Greg Low created SDU Tools to provide many general-purpose functions and utilities.
The SQLFacts suite of tools provides much of the same utility functionality with SQLFacts, Sessions, and IndexHistory.
Phil Factor (and others) have done a lot of work on identifying SQL Code Smells.
The SQLFacts suite of tools implements checking for many code smells and database smells with SQLFacts.
The tools listed above are wonderful. The SQLFacts suite of tools is wonderful as well.
The SQLFacts tools provide a lot of the same functionality, and a lot of other unique functionality, but without all the variability in style. They all use the same T-SQL code conventions and formatting.
If you choose to dig deep into the SQLFacts tools, which is not required for using them, you can begin with one tool and automatically have a great start on understanding several other tools.

What make SQLFacts different (and awesome)?

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