Hey @Katia6 ! I don’t think there is a limit on how many people can view a prototype at the same time, however, there is a limit on how many people can be in a file at once. Taking this into account, I would recommend to only share the link to the prototype, not the file.

You can check out more of Active file limits here: https://help.figma.com/hc/en-us/articles/1500006775761-Active-file-limits#:~:text=Figma%20design%20and%20FigJam%20files,cursors%20at%20the%20same%20time.