PlaceIMG might be a bit more popular than UI Filler. We know about 1 link to it since March 2021 and only 1 link to UI Filler. 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.
Working link: https://uifiller.com (I don't know how to make it a link in the body of the post). - Source: Hacker News / almost 2 years ago
Https://placeimg.com/ has some good flexibility. Source: about 2 years ago
Placemat - Pretty nice placeholder images.
Lorem Picsum - Lorem Ipsum... but for photos
Placeholder Loader Creator - SVG component editor to create placeholder loaders
PlaceKitten - Dead-easy placeholder images. Of kittens.
placeholder.pics - Lightest way to include placeholder images in your design
LoremFlickr - LoremFlickr is a service that provides free placeholder images for web and print.