Freenom®: if you do not own it, you do not have it
Freenom® offers free domain names from different countries: .TK, .ML, .CF, .GQ, and .GA.
Unfortunately: they can suspend any free domain at any time, even without providing you a reason. It is strongly advised to move away from them as soon as possible. If you move server or have unexpected downtime: your domain will be suspended without any recourse.
While it made some sense to use the domains for little personal websites or even development areas: it is better to avoid Freenom® completely.
The Freenom® reviews are out there if someone is willing to look, and for more Freenom® reviews here.