OneTrueError is described as 'Automated error management for .NET applications, including analytics and exception handling'. There are seven alternatives to OneTrueError for a variety of platforms, including Windows, Online / Web-based, Mac, Ruby on Rails and Linux. The best alternative is Raygun. It's not free, so if you're looking for a free alternative, you could try log4net or ELMAH. Other great apps like OneTrueError are Airbrake, elmah.io, Doctor Dump and NLogEx.
ELMAH (Error Logging Modules and Handlers) is an application-wide error logging facility that is completely pluggable. It can be dynamically added to a running ASP.NET web application, or even all ASP.
May be the coolest cloud based error logger for .NET web applications. Based on the de-facto standard error component ELMAH, logging errors from your webserver requires nothing more than installing a NuGet package.
Doctor Dump is a free crash reporting and memory dump analyzing service. Its work is to collect software problem reports (crashes, failures, assert violations and so on) from your customers all over the world, to group them and to give you all necessary data to fix the problem.