I have a link shortening utility. A serverless endpoint serves a SPA app (just an HTML asset with embedded JavaScript that loads a framework from the CDN) that lets me past long URLs, enter metadata, and click to generate. There is an Azure Function that takes the long URL and returns a short URL, and another that takes a short link and redirects back to the long link. I also store information about clicks in an Azure Cosmos DB instance and have a PowerBI dashboard for analytics. This lets me run the entire utility (that receives a few thousand clicks per day) for under $1/month. The database and analytics are a little more but that's a fully managed portion of the architecture, rather than serverless.