The whole list: three strings, equal weight
Copy from here, not from a forum post carrying a two-year-old link and one mistyped character.
The list at the top of this page is the whole list. Three strings, equal weight; none of them is primary, none is backup.
How to use the list
Open any one of them in Tor Browser. Before credentials, compare the string in your address bar against the row, prefix and tail. If one of the three refuses, the other two are still the same service. Nothing about your account is split across the three.
Where these strings come from
The market announces address changes inside its own app, in signed announcements; if you are already inside, you can read them. This list is unofficial and unaffiliated with the market. It republishes the strings it holds, verbatim, and monitors nothing: the address bar is the status page.
On rotation
When a hidden service redeploys, the whole string can change. That is a fact about hidden services, not a promise about any of these three. When the market publishes a different set, this list follows it.
One warning
Clones keep the name and swap characters in the middle of the string. A vanity prefix collision is a real technique, so matching the first eight characters proves nothing on its own; the tail is where a typo or a clone shows itself. Check the whole string, or run it through the checker. This page shows how the fakes get built.