Technical design documents (TDDs) are often how a technical initiative gets started at a company—and honestly, they’re the bread and butter for senior engineers. In this video, I walk through how I create a TDD using a Currency Converter Microservice example, and I build it in Confluence so it’s easy to collaborate, iterate, and keep everything in one place. I start with a simple intro section (why we even need this service), then move into an architecture overview that’s actually readable. From there, I design the architecture with a diagram (UI → API Gateway → currency converter microservice → exchange rate provider) and explain why we separate concerns: API Gateway handles auth/rate limiting/routing, the microservice owns the conversion logic, and the provider focuses on pulling exchange rates. I also add a Swagger spec right inside Confluence so other teams (like frontend) can consume the endpoints without guessing. Finally, I link Jira stories directly into the doc and show how I’d review a TDD by leaving targeted comments—like clarifying supported currencies and what “periodically updates” actually means. The big takeaway: planning up front makes implementation way less painful, and a collaborative TDD becomes your team’s single source of truth.