While you cannot make VS 2015 fully portable, you can make it portable in a managed environment .
If you need a highly portable development environment that you can carry on a flash drive or run without administrative privileges, you have several excellent, secure alternatives. Visual Studio 2015 Portable
Provides a fully configured, cloud-hosted dev environment running VS Code directly in your browser. While you cannot make VS 2015 fully portable,
* Best methods for portable Visual Studio. * Most common C++ pitfalls for beginners. * Best practices for C++ memory management. * you have several excellent