I use Google Optimize. I wouldn't call the free offering "strong."
There is a limit of about six experiments at one time. Each experiment can have up to 8 variants. And if you want more, then be ready to shell out thousands per month (I forget the exact number, but that's the ballpark).
Overall, if I were to redo things, I'd probably be better off just using Google analytics events.
Edit: that said, I'd never use a piece of bloatware like Optimizely for just the split-testing feature. If your product would benefit from split testing, then include it as a feature. It's not a "hard" feature/problem to implement into just about any existing product that would benefit from it.
Optimize can run five experiments at a time and it only lets you measure 3 metrics. Any other metrics need to be analyzed in GA and will almost certainly end up sampled and unreliable.
There is a limit of about six experiments at one time. Each experiment can have up to 8 variants. And if you want more, then be ready to shell out thousands per month (I forget the exact number, but that's the ballpark).
Overall, if I were to redo things, I'd probably be better off just using Google analytics events.
Edit: that said, I'd never use a piece of bloatware like Optimizely for just the split-testing feature. If your product would benefit from split testing, then include it as a feature. It's not a "hard" feature/problem to implement into just about any existing product that would benefit from it.