The Cat Facts SMS app was built by Akiva as a response to a Reddit post about a cat fact application that didn't exist. The app uses Google App Engine, Twilio, and TextMate to send random cat facts via SMS. The development process involved creating four files: `facts.py`, `app.yaml`, `index.py`, and `index.html`. These files were used to handle requests, interact with the database, sanitize input, and send texts using Twilio's API. The app was launched in just a few hours and received over 20,000 visits in its first day, with users able to sign up for cat facts by texting "STOP" back.