Which engineering information platform is more useful at present?

Older platforms include Tianchen, Ruidaheng and Tiangong Internet Cafe. These three platforms have been used for more than ten years, and if they are useless, they are estimated to have closed down.

Mainly compare the comprehensiveness of information content, price, virtual number and after-sales service. Tiangong. Com is more cost-effective, and the content of Ruidaheng is more comprehensive. It is up to you to choose.