There are both official and third-party ones. Every place basically has a trading center website and a government procurement website, where you can find a lot of bidding information.

Yuanbo.com is a comprehensive bidding and procurement service website operated by Beijing Guoxin Innovation Technology Co., Ltd.

Its products include "Yuanbo.com Procurement and Bidding Network", "Yuanbo.com Relationship Circle" and "Yuanbo.com Big Data" business.