Canned Emails - A minimal site with prewritten emails
Truecaller - Find a person by a name or phone number worldwide for free using Truecaller.
analyze.email - Test the spam-y-ness of your emails
Hiya - Know who's calling or texting and block spammers on Android
TestSubject - Test how your email subject line displays on mobile devices.
Credo360 - Figure out who to trust by looking at a social credit score