Those are all Tor2web proxies and your first thought should be to not use them. You first thought should be to use Tor Browser when you want to access onion services.
The contents of the following link are copy/pasted below in case the person (me) takes down their blog.
https://matt.traudt.xyz/p/mhk3vrBX.html
Why they exist
They exist so people can access onion services without using Tor. That's it. If
the user doesn't know all the caveats that come along with that benefit, then
she is probably really hurting herself. And if the user is already using Tor
Browser, there is no valid reason for her to be using a tor2web proxy. Tor2web
proxies are not a troubleshooting step. Please stop using them like one.
Please stop suggesting them to people.
Why they are bad
Payload/Session Leakage
Since the tor2web proxy is the one connecting to the onion service for Alice, it
gets to see everything. If Alice is visiting a forum or image board, the proxy
gets to see all the posts and all the images. If Alice is logging into
something, the proxy gets to see her credentials.
Let me repeat that. When you use a tor2web proxy, it gets to see EVERYTHING.
Your credentials if you sign in. Any cookies. Any uploads you make. All the
pages you request and their contents.
Onion Service Enumeration
Tor2web websites are like regular websites. Like google.com or facebook.com.
When the browser gets a request for anything.onion.to, it consults DNS to
resolve it. So every DNS server that the computer is configured to talk to (and
is told to forward its request onto by its configured servers) will find out
that anything.onion exists and someone wants to access it. If the user, Alice,
isn't using Tor Browser, then the DNS servers also find out that the someone is
her. Not good!
Even if Alice is using Tor Browser, now the tor2web proxy knows that
anything.onion exists. In fact, many have sold or still sell information on what
onion services have been requested through them. For example, see onion.cab's
list.
User/Onion Correlation
This is very similar to a point made already, but this focuses on the
consequences to the user.
The tor2web proxy knows someone is interseted in anything.onion. If the user
isn't using Tor Browser, the tor2web proxy also knows the IP of the user. If
that's not bad enough, if for some reason the tor2web proxy suspects that this
anything.onion is (almost) never accessed by anyone else, then it may conclude
that the person that just requested the onion service must be the
owner.
Real Troubleshooting
If anything.onion doesn't work for you, don't go and try anything.onion.to.
If you are using Tor Browser, and have changed network proxy settings like you
would in regular Firefox, don't do that! You are probably able to connect to
regular websites and anything.onion.to, but you won't be able to connect to
anything.onion because you aren't using Tor. You are not being secured by
Tor. The only way you should change
proxy settings is via the onion button, and you should only do that if your ISP
requires it.
If you are using Tor Browser, you didn't change proxy settings, you can access
anything.onion.to, you can't access anything.onion, and you're pretty sure
Tor/Tor Browser are working fine, then the onion service is probably down.
There's nothing you can do about it. The anything.onion.to is just a cached
copy of parts of the onion service that the tor2web proxy has fetched recently.
You aren't getting the real website and you can't interact with it. Poor uptime
is a fact of life for most onion services. They are often shortlived, are only
up a few hours each day, or both. Most are run by amateurs.
Summary
Don't play with your anonymity. Learn a little bit about how things work so you
can be safe. Adding something to the end of an onion address sounds like a good
easy way to get access to something that isn't working, but it isn't.
Slightly changing youtube.com into some other domain name that fetches the video
for you so you don't have to sign in to watch something flagged as adult is the
same idea, but at least your safety (probably) isn't at risk in that case.
