Based on our record, Facebook Design Resources should be more popular than Mockup Photos. It has been mentiond 2 times since March 2021. We are tracking product recommendations and mentions on various public social media platforms and blogs. They can help you identify which product is more popular and what people think of it.
They are from ( ublast & Free-mockups & goodmockups & mockup.photos ) and from other websites, those will help you a lot :). Source: about 3 years ago
Spotify isn't doing anything unique here, and it's not really a marketing campaign to explain away their UI. It's more of a showcase for hiring professionals, developers/designers/etc. Facebook has a similar one -> https://design.facebook.com/. Source: almost 3 years ago
Also, read anything published by Design @ Facebook. Source: about 3 years ago
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