Building a Dynamic UI System at Carousell (Part 1)

Siaw Young from Carousell reveals how they built a system that lets them update thousands of product categories without pushing app updates. The secret? A cross-platform markup language that operates at a higher abstraction than HTML.

Carousell faced a scaling nightmare: user-generated listings across diverse categories (from iPhones to jobs to insurance) needed structured data, but hardcoding forms for thousands of categories was unsustainable. Their solution was a server-driven UI system powered by 'fieldsets' that work uniformly across iOS, Android, and web.

Key Takeaways

• Fieldsets enable dynamic forms, filters, and listing views without client updates
• System handles thousands of categories updated daily across all platforms
• Declarative format controls business logic and validation, not just layout
• Solved search problems like finding '4-room' vs '3+1' vs '4bedrm' flats

Part 2 dives into the actual fieldset format and how it achieves platform independence while maintaining native performance.