Ask HN: start on my own or negotiate with the employer?

As an employee I work for a small software company developing a SaaS product, and I see a lot of opportunities to make this product much better. After all we use it on a daily basis and we’ve got plenty of experience with it. I am not talking here about incremental improvements in usability or coming up with some new cool features (although these too). There seems to be a better way to solve the same problem which the product already does by changing the product’s philosophy, its core principles and building new features on top of it. As you may guess this would require a major overhaul, or even more – complete rewrite. If this would be not enough to you, I am not satisfied with the current development platform and thinking about changing it. I have been thinking really hard and evolving this idea for the last several months and very passionate about it. I haven’t noticed someone has already implemented it, but I’m sure, if done properly, it would become a hit. Now, what should I do with my idea? Do I have to start working on a new product on my own, or should I go to my employer and convince him there’s a better way to make the same product? There are pros and cons going both ways. If I work on it on my own, I am sure it won’t be stolen and I will have freedom to implement it in the way I see it. But I will have to start a new company from scratch and attract customers one by one. If I negotiate with my employer, I will have access to the already existing resources and customers, but the tricky part to me is how to negotiate properly. Can you please give some advice about what can I do in a situation like this?