Flippa - Flippa is a platform for trading websites.
Transferslot - Easily buy and sell side-projects
buysellwebsite - Created by two California attorneys, WebsiteBroker.
AcquireBase - A marketplace for buying and selling side projects & SaaS apps for free. Absolutely 0% commission on successful sales. No paywall for unlocking offers.
Whobal - Buy and Sell Profitable Online Businesses
MicroAcquire - A free & anonymous startup acquisition marketplace