archive.today (a.k.a. archive.is, archive.ph, archive.md) is a great website and a valuable resource that I'm grateful for. That being said, it is not a long-term web archive and it is not intended to be one. This is what the site's sole owner (who is anonymous, by the way) has said about it:
Yes, the word “archive” in the title is misleading. The main purpose is to hold up ephemeral web pages for latecomers. Shots taken more than a few days ago have almost no visits.
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I don’t give guarantees. And I don’t trust the guarantees of others (like the clouds). One day it will be lost forever, just like your photos on Facebook, files on Dropbox, etc. It will happen long before the collapse of the universe.
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It is an overly optimistic assumption that there will be no risks before I die. Many projects (including at least two in this area: peeep.us and webcitation.org) stopped working long before the death of the people behind them. Many projects pivoted following the money. In addition, there are many critical points (e.g., domains) that I have no control over.
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