dotPeek
.NET Reflector
MonoDevelop
dnSpy
Zeta Resource Editor
CFF Explorer Suite
Telerik JustDecompile
MSIL Disassembler
SourceForge
GitHub
GitLab
BitBucket
openDesktop.org
Gitea
Launchpad.net
OSOR
dotPeek
SourceForge.NET Reflector - .
GitHub - Originally founded as a project to simplify sharing code, GitHub has grown into an application used by over a million people to store over two million code repositories, making GitHub the largest code host in the world.
MonoDevelop - MonoDevelop enables developers to write desktop and web applications on Linux, Windows and Mac OS X.
GitLab - Create, review and deploy code together with GitLab open source git repo management software | GitLab
dnSpy - .NET assembly editor, decompiler, and debugger
BitBucket - Bitbucket is a free code hosting site for Mercurial and Git. Manage your development with a hosted wiki, issue tracker and source code.