We are looking at some different methods for automating web tasks. Clicking buttons, filling forms, etc. I could use C# since I'm good at C++ or maybe something like Selenium, but we think we may make some useful stuff that other people would be willing to pay for. So I don't really like the C# idea since it's only going to work on Windows computers.
Ideally, the users wouldn't need to download anything, but if they need to it's okay.
We just need the ability to have the users be authenticated with us before they were allowed to use any of the scripts.
So they log in with us, then log in to whatever website that they want to do automated stuff on (like click a button 100 times really fast if you saw my other question), then they do automated stuff.
What would be the best tool for this job?