WORK NOTES ABOUT CONTACT
Frontend Engineer
Design Build Ship
Available for freelance work
FrontendPerformanceProduct DesignSystemsConversionArchitecture
Juan Carlos — Frontend Engineer
Available 40.4°N · Spain
WebsitesInterfacesSystemsLanding pagesProductsFrontendBuilt to last

I build fast, purposeful websites and digital products.

Design-trained. Product-minded. I work with agencies, startups and marketing teams that need more than someone who writes good code.

See my work Get in touch
What I do

What I bring to a project.

Available for freelance work
01
High-performance websites
Modern, fast websites built with Astro and React. SEO-ready, easy to maintain, designed to last longer than the project brief.
AstroReactSEO
02
Landing & conversion systems
Pages for campaigns, launches and lead generation. Performance and conversion are not optional.
MarketingAffiliate
03
Product interfaces
Turning ideas and flows into clean, consistent interfaces. I think in components, states and systems — not isolated screens.
SystemsStates
04
Design systems & UI foundations
Reusable component bases and token structures that let teams move faster without starting from scratch.
TokensComponents
05
Frontend architecture
Monorepos, shared packages, scalable structures. I care about how things are built — not just that they work today.
MonorepoTooling
How my work is organised

Three connected layers.

Personal layer
Jcenlo
Notes

Where I write, share experiments and think out loud about building for the web.
FrontendDesignProductPerformanceSystemsOpen source
Juan Carlos
Studio layer — client work EnloLab
StrategyDesignFrontendPerformanceArchitectureBuilt to last
Technology layer
Saastro
Performance Product Craft

For the Builders Shaping the Web.

Building isn't just writing code — it's turning ideas, flows and constraints into products that perform. Design, execution and results, working together.

(Projects shipped) 60+ Websites, product interfaces and landing systems — built to perform and to last longer than the brief.
(Years building the web) 8+
Frontend Performance Product Systems Conversion
(Graphic design) ∞
Branding Visual identity Typography Layout Art direction

Ready to build your next project?

Whether it's a website, a product interface or a campaign landing system — let's make something that works.

Start a project
Juan Carlos
Notes

On building for the web.

All notes →
17 Mar
Why I no longer use Figma
designAIworkflowfrontend
16 Mar
saastro-relay: persistent memory for working with AI on real projects
AIMCPtoolingarchitecture
15 Feb
Design systems with AI: what changes and what doesn't
designAIsystems
20 Jan
UX writing: words are interface
UXwritinginterfaces