Test to determine the server being used to resolve your DNS queries
Fun tool to get a rough time estimate for written work
freeTSA.org "provides a free Time Stamp Authority. Adding a trusted timestamp to code or to an electronic signature provides a digital seal of data integrity and a trusted date and time of when the transaction took place."
FreeTSA also offers an NTP server and no-log resolvers supporting DNSCrypt(/DNS/resolvers/DNSCrypt.md) or DoT.
Free service to check if a site is down
The pool.ntp.org project is a big virtual cluster of timeservers providing reliable easy to use NTP service for millions of clients.