A key challenge in file transfer is identifying each user. Apple's AirDrop leverages a user's OS-level ID, but since I was building a web app, I needed to generate an identifier.

What kind of ID, though? Since users would typically share itverbally, using letters was risky—phonetically similar ones could cause confusion. Numbers seemed like a simple solution, but they weren't memorable, and similar-looking numbers could lead to mix-ups. Also, a search box would have been necessary to help users find the right match. Plus, numbers lack personality!

The solution? A system that paired an animal with a personality trait—like “Adaptable Emu” or “Gregarious Magpie.” These names were amusing, easy to remember, and distinct enough to prevent miscommunication. And as a bonus, they added a bit of personality—because a smile on a user's face is always a win!

Since this was a web app, it could potentially be used by people across different countries, leading to thousands of users at any given time—and a lot of searching to find the right person. However, the most common use case was likely to be two people sitting next to each other, wanting to transfer a file.

Geo-location could have helped, but it would require permission requests, adding unnecessary friction. Instead, I found a more elegant solution: grouping users by their local network. While users on the same network have different private IP addresses, they share the same external IP address. By having each client ping a server to retrieve their external IP, I could group users accordingly in the database. This ensured that only people on the same network appeared in search results—usually just one other person—making the process as seamless as possible.