I started working on Gatekeepr on July 27, 2025.
It came out of a problem we had at WebScrapingAPI: the same user creating multiple accounts to keep using the free trial. A new email address, another account, another free trial. We needed a better way to understand what was happening when someone signed up.
Most of the verifications we were doing were heuristic. We looked at the email format, the separators people used, the domain, and whether it appeared on a list of disposable email providers. These checks gave us something to work with, but I wanted to go deeper and see how far I could get.
So I started building Gatekeepr as a research project. I wanted to understand how much you can learn from an email address and the information around it. What else could I check? Which signals would be useful? And how much of this could I automate?
I added DNS lookups, IP lookups, and more verifications. I also compiled multiple lists of disposable email domains into a single one. Instead of looking at these checks separately, I wanted to bring them together and get a clearer picture of a signup.
There isn't one check that tells you everything. An email address can look normal and still be used to create another free trial account. That was what kept me interested in the project: going beyond the obvious checks and seeing what else I could find.
Eventually, I had to spend time on the other part of building a product: sales and bringing it to market. I didn't have enough time to focus on that part.
So I decided to open source it. I'd rather put the code out there, where someone else can use it, read it, or build on it.
You can find Gatekeepr on GitHub.