dotnet has been out for many years and currently in the year of our lord 2020 we have long-term support, three years of support, It's open source all the way down to the metal and it runs on Mac and Ubunto and all the different Linuxes and Docker, it runs everywhere!

I was reading this sentence that is about ".NET" which is one of the concepts of programming language made by Microsoft, but I didn't understand the part " It's open source all the way down to the metal ".

Can anyone explain it to me?

2 Answers 2


In computer programming, "the metal" is slang for the actual computer hardware itself. For a program to run, there are several layers of computer languages that run to eventually make the computer perform the correct actions. For example, "machine language" is the code that directly tells the computer what to do, and it's all "zeros" and "ones" which turn specific transistors on or off. Above that is "Assembly language", which is a human-readable version of machine language that uses letters, numbers and other symbols. Above that there are some other layers of programming, all the way up to the highest level programming language used in the project.

The claim here is that all those layers are open-source

  • That was very helpful, thanks a lot. Sep 23, 2021 at 6:48

Open source means that the source code for the software is openly available: it isn't proprietary (someone's private property). "Down to the metal" means that all levels of the software are open source, from the user interface down to the computer hardware (the metal) that the software runs on.

It's likely an exaggeration, though.

  • Indeed, it's rather tricky to tell where hardware ends and software starts these days. But the claim seems intrinsically wrong to me in that .NET doesn't go all the way down to the "metal", there's an operating system in between. However the meaning of the phrase is clear even if the statement is false. May 19 at 10:37

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