“PS Buy and Sell” application is the ready made complete classified platform application like Olx, Mercari, Offerup and Carousell. It is easy to setup and no coding required.
Demo: https://codecanyon.net/item/ps-buy-sell-olx-mercari-offerup-clone-classified-app/24220109
source http://www.codelist.cc/mobile/241141-ps-buysell-v28-olx-mercari-offerup-carousell-buy-sell-clone-classified-app.html