July 03, 2025

SDUI at Scale: GraphQL & Elixir at Cars.com with Zack Kayser

49 minutes

Zack Kayser, Staff Software Engineer at cars.com, joins Elixir Wizards Sundi Myint and Charles Suggs to discuss how Cars.com adopted a server-driven UI (SDUI) architecture powered by Elixir and GraphQL to deliver consistent, updatable interfaces across web, iOS, and Android.

We explore why SDUI matters for feature velocity, how a mature design system and schema planning make it feasible, and what it takes, culturally and technically, to move UI logic from client code into a unified backend.

Key topics discussed in this episode:

SDUI fundamentals and how it differs from traditional server-side rendering

GraphQL as the single source of truth for UI components and layouts

Defining abstract UI components on the server to eliminate duplicate logic

Leveraging a robust design system as the foundation for SDUI success

API-first development and cross-team coordination for schema changes

Mock data strategies for early UI feedback without breaking clients

Handling breaking changes and hot-fix deployments via server-side updates

Enabling flexible layouts and A/B testing through server-controlled ordering

Balancing server-driven vs. client-managed UI

Iterative SDUI rollout versus “big-bang” migrations in large codebases

Using type specs and Dialyxir for clear cross-team communication

Integration testing at the GraphQL layer to catch UI regressions early

Quality engineering’s role in validating server-driven interfaces

Production rollback strategies across web and native platforms

Considerations for greenfield projects adopting SDUI from day one

Zack and Ethan's upcoming Instrumenting Elixir Apps book

Links mentioned:

https://cars.com

https://github.com/absinthe-graphql/absinthe

Telemetry & Observability for Elixir Apps Ep: https://youtu.be/1V2xEPqqCso

https://www.phoenixframework.org/blog/phoenix-liveview-1.0-released

https://hexdocs.pm/phoenix_live_view/assigns-eex.html

https://graphql.org/

https://tailwindcss.com/

https://github.com/jeremyjh/dialyxir

https://github.com/rrrene/credo

GraphQL Schema https://graphql.org/learn/schema/

SwiftUI https://developer.apple.com/documentation/swiftui/

Kotlin https://kotlinlang.org/

https://medium.com/airbnb-engineering/a-deep-dive-into-airbnbs-server-driven-ui-system-842244c5f5

Zack’s Twitter: https://x.com/kayserzl/

Zack’s LinkedIn: https://www.linkedin.com/in/zack-kayser-93b96b88

Special Guest: Zack Kayser.

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By SmartLogic LLC

4.9

2222 ratings