can you link me some free third level domain services that allow full control over all records? while I don't need it now, in the past I have wanted such a service and was unable to find them.

"All records" makes an important difference indeed. I mostly thought about web projects where you need A / AAAA and CNAME. I do remember that I had access to MX and TXT at some free provider around 1995; GeoCities? Can't remember.

Sitelutions.com still offers this. Without a paid account, the only limitation is the TTL.

So far I've only found https://nic.eu.org/ but it works, and I assume it's unlikely to go anywhere for the foreseeable future.

for $8 a year you can get a regular domain and then have as many free 3rd level domains with full DNS control as you want. or do you really just mean free free

based on the top level comment, I guess free free; something a child without a credit card can use on his own while playing around

Yeah, the refrain is usually "anyone should be able to afford $8 a year", but I remember being teenager and even when I was making an income I still couldn't get a credit card. It's less about the money and more about the ability to pay.

You don't really need credit cards, we found ways to pay for domains and hosting back in the day when we weren't legally able to get one (due to being minors). Some smaller companies accept other ways to pay that can be used anonymously. I definitely couldn't afford $8 a year thought, so others were covering that.

Even if you can't get a credit card, most banks will give you a debit card at 13.

Not in the part of the world I lived in, plus debit cards here work on local only sites whereas registrars are non-local.

It requires specific care because in the DOM security model, third level sites are all in the same security domain and can read each others cookies and control each others pages. The browsers have a special list with gov.uk, co.uk etc so it knows these are special.

That wasn’t a concern in 2002 but today it should be.