speq

There's also URLCheck:

https://f-droid.org/packages/com.trianguloy.urlchecker

https://www.archivebuttons.com/ is the way

Also: https://standardebooks.org/

Thank you very much! Unfortunately after confirming the information in the signup dialog, it says "Please wait" and hangs. Is it me?

Edit: It works on the second try on the computer, thanks again

Matrix is very good and flexible. If you need something that is interface-compatible with Discord, there is: https://revolt.chat/