SimpleX Chat: private and secure messenger without any user IDs (not even random)
Session Protocol: Technical implementation details - Session Private Messenger
Shortened URL Security / safecomputing.umich.edu
Use the shortening service preview feature. Type the shortened URL in the address bar of your web browser and add the characters described below to see a preview of the full URL:
tinyurl.com. Between the "http://" and the "tinyurl," type preview.
Example: http://preview.tinyurl.com/zn7xnzu
bit.ly. At the end of the URL, type a +.
Example: http://bit.ly/2lgPesi+
goo.gl. At the end of the URL, type a +.
Example: https://goo.gl/vLfoaW+
Use a URL checker. These are just a few of the sites that let you enter a short URL and then see the full URL:
getlinkinfo.com
unshorten.it
urlxray.com
Signal crossplatform list of features
Unofficial Wiki