The author, a developer, built a side project called Hustlin to help people in San Francisco know when baseball games are happening. The original version used Ruby on Rails and Heroku, but the cost of hosting was $7 a month. To reduce costs, the author switched to using AWS's Serverless Framework, which allows functions to execute on-demand and scale with no additional cost. By using this framework, the author was able to host the API for free and save 100% of the previous year's hosting cost. The project now uses DynamoDB to store data and cron jobs to send notifications.