Archive.st is described as 'Free web page archiving service' and is a Web Archiving Service in the Education & Reference category. There are more than 10 alternatives to Archive.st, not only websites but also apps for a variety of platforms, including Mac, Windows, Linux and Android. The best alternative is Wayback Machine, which is free. Other great sites and apps similar to Archive.st are Archive.is (Free), ArchiveBox (Free, Open Source), TechRewind (Free) and Time Travel (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.