Design System Mercado Público

Mercado Público is Chile’s government procurement platform — hospitals, municipalities, and ministries use it daily to acquire everything from medical supplies to infrastructure services. With over one million active users and billions in annual transactions, inconsistency has a direct cost.

When I joined to lead the Design System, the core problem was not the absence of components. It was the absence of design authority. Five product teams were building independently, each applying their own content conventions. Some flows read like legal filings. Others read like internal IT memos. None of them sounded like a platform built for people.

The system had visual foundations. What it lacked was a shared criterion: a principled approach to deciding what to say, how to say it, and why it matters. That gap was visible in every screen — buttons that introduced doubt instead of resolving it, error messages that reported failures without offering paths forward, labels that were only legible to people who had been on the team for years.

Before proposing any solution, I ran a diagnosis of the current state of content. I reviewed complete flows, labels, system messages, CTAs and internal documentation. What I found was revealing.

Before defining principles, I needed a practical filter — a single question that any team member could apply to any piece of content, without specialized training in UX writing.

The Design System was organized following atomic design principles, with an additional layer not usually present in traditional systems: content guidelines as a constitutive part of the system, not as an appendix.

To establish a consistent and sustainable visual system, we defined a three-level token architecture. The logic: any global change, a rebrand, a new theme, could propagate from a single place.

What I learned building this library is that a component without content criterion is just a shell. A button without a labeling guide can create confusion. An error message without a writing pattern can frustrate at the worst moment.

Every component in the library was designed with its states, variants and interactions, but also with its content guidelines integrated directly into the documentation.

This was the part of the system that was hardest to argue for and had the most impact. The content guidelines did not live in a separate Drive document. They were integrated into the system with the same weight as typography or colors.

Mercado Público has a particularity that complicated some decisions: its buyer users are experts in public procurement. That means there are technical and legal terms that cannot be eliminated. Tender, direct purchase, award, these are concepts from the professional vocabulary of the people who use the platform.

The challenge was not to simplify at any cost. It was to find the balance where necessary technical language coexists with the greatest possible clarity for those who are just getting started. That nuance was explicitly documented in the system.

The system was not delivered all at once. It launched incrementally, prioritizing the highest-use components and the most urgent guidelines first. At each stage, feedback was collected from the teams using it.

The content guidelines were integrated into the Design System with the same weight as typography, colors or components. Not as an appendix. As a living part of the system, accessible in the same tool where teams design.

That changed something concrete: teams stopped making content decisions intuitively and started having shared criteria. Reviews happened earlier in the process. The platform started to sound more consistent, more coherent, more human.