Flexibility is complexity in disguise: Building frappe-ui for 10+ Products

Frappe UI is a Vue component library that, over several years, became the foundation for many Frappe products like Frappe Cloud, Gameplan, Helpdesk, CRM, and Drive. One library serving many products. I also built Gameplan, one of the products on top of it, so I designed these APIs from both sides, as the library author and as the app developer who has to live with them every day. This talk is about the discipline that makes that work: a deliberately small, opinionated public API. Open source tools usually stay flexible so they can plug into anything, but flexibility is just complexity in disguise, and frappe-ui takes the opposite bet. I cover how we name components and props so people can guess them, why we pick strong defaults over endless configuration, and how we say no as every product asks for one more prop.

It also covers the part most design systems skip, which is data. frappe-ui ships first-class, opinionated data-fetching utilities (useDoc, useList, useCall) built for Frappe backends, because a real product design system has to answer how you load and save data, alongside what a button looks like.

When AI agents started writing frappe-ui code, the same opinionated, predictable API that served people also worked well for agents. The discipline we built for humans is what made the library agent-ready.

• Be opinionated, even in open source. Flexibility is just complexity in disguise.

• A design system is more than components. Give products an opinionated way to load and save data too.

• Make correct usage the path of least resistance, and mistakes hard to miss.

• A predictable API serves new teammates and AI agents alike.