Legal Question in Business Law in California

It depends on the type of business and products you are contemplating selling. You will, at least, need to get a business license in the city where you do business. If you set up a company, which probably is a good idea, then you will need to take care of the paperwork and filings to set up the company, too.

Most municipalities, including Cotati, expect all businesses to obtain licenses, without respect to how the business is conducted. If you are a business, you need a business license, whether you do your deals by computer, telegraph, smoke signals or what-have-you.

Having said that, I'd add that getting a business license is a trivial expense and bother in comparison with the other aspects of starting and running a business. It is not the tip of the iceberg, it is a tiny corner of the tip.