Face Swap GIF lets you upload a short GIF or video and a face photo, then produces a version with the face replaced. For clips with several people, a multiple-faces mode lets you choose who to swap.
It is free with no sign-up, and files can be up to around 10 MB and 30 seconds long. You preview the result and download it as a GIF. The site asks users to confirm they are allowed to use both files.
