p33photography

Hi Michael_Kornmann, 
Squarespace supports JPG, PNG, and GIF image files. It is recommended using images that are between 1500 and 2500 pixels wide and under 500 KB. You should also keep overall page size under 5 MB for loading time optimization. For more image best practices, check out this help guide:
Formatting your images for display on the web
 

Hi, tried to load pictures in WebP format which is not accepted by SQ, same with JP2 format. Need to improve the speed of the page by improving the format and size of the used pictures.

In the developer notes, Apple notes that it has added WebP image support for the first time in Safari.

With all browsers supporting WebP, and Google prioritizing image loading speed in rank, I certainly hope Squarespace will provide the ability to host these images - which are quickly becoming an industry standard.

I would also love to see .webp support ASAP.

It's 04/07/2022 and today I confirmed .webp is still not supported by Squarespace.
That's unacceptable.

Still an issue - not supporting webp puts Squarespace in an elite group - just them, and internet explorer.

24/03/2022 and still no progress? 

Google has stated that come May 2021, this will be a direct ranking factor.
So this is one more arrow in the quiver of those asserting that SS is bad for SEO.
In this case, Google has told us that using the old JPG or PNG types is decidedly bad for SEO.

Yes, please allow WebP. As others have said, it's almost a requirement now from Google, and it wouldn't take any development time on the part of SquareSpace. This is very concerning.