It partly depends on your definition of startup. But sure, you can start up your web app on the side and hope to gain traction. But problem is just that you a

It partly depends on your definition of startup. But sure, you can start up your web app on the side and hope to gain traction. But problem is just that you are at a disadvantage since you don't have full time to devote to the project. That means you can't add features, respond to user requests, market, expand as quickly as your competitors who are full time.