Senior Frontend Engineer · Ciudad de la Costa, Uruguay
Diego Díaz
Human judgment, machine speed.
I design and build product interfaces and the design systems behind them. I use AI to move faster, and I stay accountable for every decision it touches.
- building for the web
- 17 years
- Next.js, React, React Native
- Design systems
- with Claude Code, reviewed by people
- AI workflows
Selected work
Products, systems and the way teams build them
Each case study shows the decisions I made, the results, and where AI helped.
Founder · Product, design and engineering
Karma Plus
People log good deeds they did or witnessed, and together they fill an anonymous heatmap. Web and mobile share one design system, and Claude Haiku checks each submission before it goes live.
- Design thinking
- Next.js
- Expo
- Supabase
- Claude API
Personal project · Claude Code tooling
AI Toolkit
Sets up Claude Code on any repo: it maps the project, pins what works today as a baseline, and generates the agents, hooks and skills to build new features without breaking old ones.
- Claude Code
- Skills
- Hooks
- Agents
- Developer experience
Not public yetFrontend Lead
Freedom Robotics
A 0 to 1 fleet management app for robots. I redesigned how it used the API, cutting query load by 90% and perceived delays by 75%, and built the internal SDK the app used to talk to it.
- React
- TypeScript
- SDK
- Performance
Personal project · Design and engineering
Ramps: a design system study
A study of Ramp’s design system and Bill Pay app, rebuilt from their public product videos with a Claude Code skill I wrote: 40 components and nearly 200 stories in Storybook, plus a working demo backed by Supabase.
- Design systems
- Storybook
- Next.js
- Supabase
- Claude Code
Personal study. Not affiliated with Ramp.
Design and engineering
The design system behind this site
Tokens, accessible components and motion in a monorepo, documented in Storybook and tested on every story. Built faster with AI, with every change reviewed.
- Design tokens
- Storybook
- WCAG 2.2
- Motion
- Monorepo
Also built
- Călător (opens in a new tab)
A booking MVP built mobile first: one smooth checkout on the phone instead of a long list of features. Next.js, libSQL, Drizzle and shadcn/ui.
About
Designer at heart, engineer by trade
I studied advertising and creative communication in Buenos Aires and started as a graphic designer. I moved into frontend development because I wanted to build what I was drawing. Today I work where design, product and engineering meet: design systems, Next.js, React Native and product architecture.
I was born in Argentina and live in Ciudad de la Costa, Uruguay. I have worked remotely with teams in the US and Latin America since 2011, I have been a Toptal Verified Expert since 2017, and I am the founder of Karma Plus.
How I work with AI
I decide, AI accelerates
I define the problem, the architecture and the quality bar. AI drafts code, variants and tests faster than I could type them.
Everything gets reviewed
Code that comes from AI goes through the same review, tests and accessibility checks as code I write by hand.
Systems over prompts
I build shared context, rules and tooling so a whole team gets consistent results, not lucky ones.
Experience
Senior Frontend Engineer
Method (opens in a new tab), –
- Championed AI-driven development: team practices, context files and review guidelines for Claude Code and MCP.
- Migrated core features to TypeScript and moved state management from Redux to React Context.
- Built the Bills feature end to end, and the Shop feature from concept to deployment with SKU lookup and barcode scanning.
- Partnered daily with Product on strategy and UX, and helped keep the product SOC 2 compliant.
Frontend Lead
Freedom Robotics (opens in a new tab), –
- Joined through Toptal and was later hired by the company to build a 0 to 1 app.
- Redesigned how the app used the API: 90% less query load and 75% shorter perceived delays.
- Built the internal SDK the app used to talk to the API, and a vetted UI kit that improved engagement and developer experience.
Frontend Consultant
Seabury Solutions (opens in a new tab), –
- Core team for an internal AngularJS framework used by other teams to build aviation software.
- Co-designed an N-layer form architecture with dynamic components, UI Router, DevExtreme and a shared OData store.
Senior UI/UX Engineer, Verified Expert
Toptal (opens in a new tab), – present
- Clients include MIT Media Lab, The Catch Company, Humanity Forward and Sepia River.
- Rebrands, UI kits, Sass architectures, React and AngularJS apps, and full rewrites.
- Wrote How to Build CSS-only Smart Layouts With Flexbox (opens in a new tab) for the Toptal blog.
Contact
Let’s build something people enjoy using
Open to senior frontend and design engineering roles, and to consulting on design systems and AI adoption.