dnSpy (original author: 0xd4d; maintained by dnSpy open-source contributors)

dnSpy is an open-source .NET debugger, assembly editor and decompiler originally authored by the GitHub user known as 0xd4d. The tool combines a managed-code debugger, IL and C# decompilation, and on-the-fly editing of assemblies. It has been widely used by developers and reverse-engineers for inspecting, debugging and modifying .NET binaries, and became popular because it packages decompilation, editing and debugging in a single desktop application.

There is no formal commercial company behind dnSpy; development began with the individual author (0xd4d) and continued through contributions from an open-source community. The project's primary home and distribution point is its GitHub repository, and various community forks and continuations exist. The codebase is published under an open-source license (commonly MIT in references), and the project is maintained by volunteer contributors rather than a corporate entity.