start on my own or negotiate with the employer?
russell: Dont start working on a competing product while still at your current employer.  You probably have an employment contract that gives them the right to your work.  (This is different from working on something totally unrelated.)How you approach your employer depends greatly on the corporate culture and your immediate supervisor and his/her boss.  If no one else has side projects or if every minute has to be accounted for in reports or timesheets, your chances are not good.  If the culture is a little more open and you have a good relationship with your boss, you could try for 20% time to explore your ideas.I am guessing you are young.  It takes a while to build up corporate political savvy.  I tried just such a thing early in my career and was promptly fired.  If you have a colleague with more experience in the company's political arena, have a beer and talk about your thoughts on changes, but not about going out on your own.I am a strong believer in the future of enterprise SaaS, but such a startup needs much more that the YC level of support.  Make a prototype for sure, but be prepared to raise 6 and 7 figures to transition to profitability.