Presentation: API-First Architecture Transformation at Etsy



10:35am - 11:25am

Day of week:




At Etsy we have been doing some pioneering work with our APIs. We switched to API-first design, have experimented with concurrency handling in our composition layer, introduced strong typing into our API design, experimented with code generation, and built distributed tracing tools for API as part of this project.

We faced a common challenge: much of our logic was implemented twice. All of the code that was built for the website then had to be rebuilt in our API to be used by our iOS and Android apps. We wanted an approach where we built everything on reusable API components that could be shared between the web and API. Unfortunately our existing API framework couldn't support this shared approach. The solution we settled on was to abandon the existing framework and rebuild it from scratch.

Follow along this case study of building an API First architecture. Hear what problems prompted this drastic change. Learn which new tools we had to build to be able to work with the new system and what mistakes we made along the way. Finally, how did it end? How did the team adopt the new system and have we succeeded in our goals of API First?

Speaker: Stefanie Schirmer

API Lead @Etsy

Stefanie Schirmer is a Software Engineer at Etsy and an alumna of Hacker School in New York. She studied Applied Computer Science in the Natural Sciences in Bielefeld, Germany, where she developed a type checker for a compiler of a language for optimization problems. In her following PhD project she developed metrics for the structure comparison of RNA molecules. Working as a postdoc in Montréal, Canada, she found her way to Hacker School and to Etsy in Brooklyn and Berlin. In Etsy's core platform team she is working on the API that connects the community of buyers and sellers across different devices.

Find Stefanie Schirmer at


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