WebBen

Is a tool for benchmarking your Hypertext Transfer Protocol (HTTP) server.

NsDepCop

Static code analysis tool to enforce namespace dependency rules in C# projects.

Bencher

Suite of continuous benchmarking tools designed to catch performance regressions in CI.

BenchmarkDotNet

Powerful .NET library for benchmarking.

AspNet.Metrics

Capturing CLR, application-level web request metrics. Middleware and extensions using Metrics-Net

Metrics-Net

The Metrics.NET library provides a way of instrumenting applications with custom metrics (timers, histograms, counters etc) that can be reported in various ways and can provide insights on what is happening inside a running application

Gendarme

Extensible rule-based tool to find problems in .NET applications and libraries. It is part of Mono that is been discontinued.

StyleCop

StyleCop analyzes C# source code to enforce a set of style and consistency rules

CodeMaid

CodeMaid is an open source Visual Studio extension to cleanup and simplify our C#, C++, F#, VB, PHP, PowerShell, R, JSON, XAML, XML, ASP, HTML, CSS, LESS, SCSS, JavaScript and TypeScript coding

App.Metrics

App Metrics is an open-source and cross-platform .NET library used to record and report metrics within an application and reports it's health. See the docs for me details.

NDepend

Is a Visual Studio and VS Team Services extension that estimates your .NET code quality and Technical-Debt, that lets create code rules with C# LINQ syntax, visualize code structure and focus on changes and evolution. [$]

PVS-Studio

PVS-Studio is a static analyzer on guard of code quality, security (SAST), and code safety. [Free for OSS] [$]

.NET Compiler Platform ("Roslyn") Analyzers

A number of Roslyn diagnostic analyzers initially developed to help flesh out the design and implementation of the static analysis APIs.