I have never heard of that service (looks pretty interesting actually), but at the bottom it says trust by Uber, Pinterest, Google, etc.
Does this mean these companies are outsourcing their graphics, mock ups, etc.?
Does this mean these companies are outsourcing their graphics, mock ups, etc.?
On the other hand "Used by X" can mean anything from "X uses us as a core part of their workflows" and "A small team at X uses this sometimes". So don't give it much weight.
For example, even though Salesforce obviously has a lot of talented programmers on the payroll, I wouldn't be at all surprised if the Dreamforce conference website is built by a separate firm.