Currently, Foxy's limits are as follows.
Items in your Product & Feed section:
Photos: Are currently limited to 20 megabytes per file and the image can not be larger than 8192x8192 pixels.
Videos: Have no file size limits in duration or in file size. So you'll have no problem uploading that 4K file from your iPhone.
Note: The bigger your files are, the longer they will take to upload (depending on the speed of your internet connection). It's always recommended to be on wifi for those larger files. No one likes to wait around.
Chat: Currently we support up to 500MB Videos (that's about 7 minutes of full HD video from your phone) and photos at full 8192x8192 pixels.
**Technically speaking we do have a limit of 16 hours of 4K video, but uploading that would take several months.