@arjay_mccandless — 25x breakout

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Did you know that users keep creating new accounts to get unlimited free trials?

@arjay_mccandless

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Why it worked

The video uses a clear, relatable technical problem and a 'two-person' dialogue format to explain complex system design concepts in an accessible way.

Summary

A developer explains the technical challenges of preventing free trial abuse in software systems. He discusses the pros and cons of using IP addresses and device fingerprinting before proposing a multi-factor risk scoring system.

Structure

1Identify the problem of free trial abuse
2Evaluate IP-based blocking
3Evaluate device fingerprinting
4Propose a comprehensive risk scoring system

On-screen text

Trial Events Log 12:01:03 user_123 TRIAL_START 12:01:18 user_123 TRIAL_CANCEL 12:05:41 user_123 TRIAL_START 12:05:57 user_123 TRIAL_CANCEL 12:10:12 user_123 TRIAL_START 12:10:26 user_123 TRIAL_CANCEL

Transcript

Did you know that users keep creating new accounts to get unlimited free trials? We have to stop them. That's really bad. How about we only allow one trial per IP? We could do that, but then a bunch of actual users won't be able to get free trials. What if there's four people living together on the same home network behind the same IP trying to start a trial? All these users will fail because this guy's abusing trials. Okay, that makes sense. What about something like device finger printing then? Okay, you mean like trying to put together a unique ID for each user based on things like their operating system, screen resolution, browser they're on, language and time zone? Yeah, exactly. Okay, that seems closer, but I think users could still get around this by doing things like changing their browser and time zone. Okay, well, what do you think we should do? I think we should combine everything we've talked about like their IP, their device fingerprint, and even their payment method to create a risk score per user. And if it exceeds a certain number, we probably shouldn't let them start a trial. Some duplicates might slip through, but this should catch the majority of users.