Seeed Studio was one of the first PCB manufacturers on PCBShopper. Today, we’ve added them to our PCB assembly list as well. Seeed provided a straightforward API to fetch assembly prices which made them easy to add.
Seeed’s online form combines PCB manufacturing with assembly, whereas PCBShopper prices them separately. So if you want Seeed to assemble boards that they did not manufacture, you might need to contact them directly.