Is there any free tool to help obfuscation the files code ?
Thanks
The term for what you're looking for here is obfuscation, that will probably help future searches/questions.
Visual Studio 2019 has a free add-on that supports some obfuscation, here's the link to the MS documentation on how to install it: https://learn.microsoft.com/en-us/visualstudio/ide/dotfuscator/install?view=vs-2019
That tool is actually a third-party tool called Dotfuscator, and this is their free Community edition. They have higher tier products as well that provide additional protection, but they cost money. There are other obfuscation products out there as well (both free and paid), and you generally get what you pay for in terms of quality and support. With all of them, make sure you're doing extra testing since obfuscation can break certain types of things.
Some others you may want to look at: