I want to open source an HTTP Client for a closed source software product.
The vendor of this product distributes the binary packages / executables only in forums / repositories which require proper authentication. In addition, the product requires a license key to be usable. Without this key, the program would not work.
My overall impression is that this vendor prefers to not publicly expose both documentation and the actual software but instead wants to control who has access to their software.
My question: Can I open source an HTTP client for the API which this software product exposes? And if so, are there license models which I should avoid?