Ask HN: How to control users abusing the free credits and demo

Welcome to my world. We're in year 5 and no amount of checking for multiple signups by IP, block/spam/burner email lists, captchas, questionnaires, email confirmation, oauth logins (google, facebook) helps. Multiple signups for free stuff come from students, whole universities (we found our service listed in several curriculum with "just sign up for free") and Fortune 500 companies. Record was a user with 100 accounts. Written warnings works somewhat but also get ignored regularly. After IP blocks our last defense is returning fake data.

While frustrating we see it was daily business to block some users. Overall it costs us time but rarely lost revenue. Those users willing to register 10 accounts don't convert to paid accounts much.

Free trials requiring credit card will help, it's more work to setup and will lower the number of signups.

So far it doesn’t seem like they’re dedicated attackers trying to abuse the service but more like legitimate users just using the free service without concerns for paying because you don’t prevent them from using it freely.

So restrict the free tier to an amount that allows them to try it while limiting intensive usage, and then ask for a prepaid entry/starter plan for more (don’t just rely on active credit cards as they can be generated infinitely - you need to actually take money from them).

Add something that will show people how the system works. A short demo or video that just shows the input and the results. That will cut down on the number of users using the service just for curiosity.

Also, keep in mind that only a small percentage of the people that use the system will signup to pay so don't be surprise of the number of people trying the system for free versus signups.