Archive.is is described as '(previously named archive.today) allows you to "take a photo" of a webpage that will always be available even if the original page changes or is deleted' and is a popular website in the Backup & Sync category. There are more than 10 alternatives to Archive.is, not only websites but also apps for a variety of platforms, including Self-Hosted solutions, Mac, Windows and Linux. The best alternative is Wayback Machine, which is free. Other great sites and apps similar to Archive.is are ArchiveBox (Free, Open Source), Archive.st (Free), Archive-It (Free) and TechRewind (Free).
Because modern websites are complicated and often rely on dynamic content, ArchiveBox archives the sites in several different formats beyond what public archiving services like Archive.org and Archive.is are capable of saving.
Free online service for freezing web pages. Save, share and prove what is on the web at a specific point of time. You have to register a free account and to log in every month otherwise your frozen pages won't last more than 3 days.