Skip to main content
Leonardo Serrano Leonardo Serrano
Leonardo Serrano
Open to opportunities

Leonardo Serrano

Full-Stack Engineer

Herediana de Siquirres, Limón, Costa Rica

Full-stack engineer with 13+ years deploying production software in Costa Rica. Founder of FLProductions (a recording studio that brings 80% of its clients through its website) and co-founder of Zamr (a multi-tenant SaaS for worship bands, load-tested to 500 concurrent users). Currently building MejorMenu, a multi-tenant SaaS for restaurants in Herediana de Siquirres, Limón.

leovpc@gmail.com +506 6301 7707 @Leotheprodu leonardo-serrano-dev
Get in touch

Highlights

Real metrics from 13+ years of production work.

13+ years shipping production
4 live products
~159K lines of code
Top 3 SEO in Costa Rica
500 concurrent WS users
156 test files (>=80% cov.)

Experience

Three products shipping to real users every day.

#1 FLProductions

Founder · Full-Stack Engineer

2013 to present (13+ years) · Herediana de Siquirres, Limón, Costa Rica

  • Built and maintained the studio website, artist portal, and beat e-commerce in a single NestJS + Next.js monorepo: 28 Prisma models, 202 REST endpoints, 41 real-time event listeners.
  • Top 3 in SEO for "estudio de grabación" in Costa Rica. The website brings 80% of the studio's clients.
  • Implemented a real-time wallet with 5% cashback, tiered vault pricing, an AI chat (GPT-4o-mini) that parses Costa Rican Spanish and books appointments, and Google Calendar two-way sync.
  • Cost engineering: cron jobs auto-move files to GCS Coldline after 30 days of inactivity, achieving about 80% storage cost reduction.
NestJS 10 Prisma 5 Next.js 15 PostgreSQL Socket.IO Tailwind CSS Google Cloud Storage PayPal OpenAI
#2 Zamr

Co-founder · Full-Stack Engineer

2024 to present · Heredia, Costa Rica (remote-first)

  • Built a multi-tenant SaaS for worship bands and churches: 18 NestJS modules, 28 Prisma models, 131 REST endpoints, 3 WebSocket gateways.
  • Wrote a 1,023-line WebSocket gateway with per-user rate limiting, message compression (60% payload reduction), priority preemption, and JWT auto-refresh that survives Railway cold starts.
  • Load-tested to 500 concurrent WebSocket users: 156 test files, >=80% coverage enforced, 500+ songs catalogued, 100+ live events powered.
  • Two distinct live views: projector (lyrics plus animated backgrounds) versus musician (chords plus dark). Login with Google OAuth, no passwords stored.
NestJS 10 Prisma 5 Next.js 15 Socket.IO MySQL HeroUI TanStack Query Nanostores Google OAuth
#3 MejorMenu

Founder · Full-Stack Engineer

2026 to present · Herediana de Siquirres, Limón, Costa Rica

  • Multi-tenant SaaS for restaurants in Herediana de Siquirres, Limón: 3 live clients in the first weeks.
  • Each business gets its own public page at /[slug] with menu, hours, location on a map, and an order button that opens WhatsApp with a pre-formatted message.
  • AI image generation with Google Gemini (3 context types: menu items, logo, cover). Credits are consumed before each call.
  • Built the full flow: catchHandle pattern, deny-by-default permissions, PostData with declarative cache invalidation, useSocketSync dispatcher, timezone-aware business hours, and bulk menu import from plain text.
NestJS 11 Prisma 6 Next.js 16 MySQL Google Gemini Tailwind CSS Leaflet TanStack Query

Languages

  • Spanish (native)
  • English (professional working)

What I work on

  • Real-time systems
  • Multi-tenant architectures
  • Developer experience
  • AI integrations

Like what you see?

Open to interesting projects, contract work, and full-time roles where the team ships production software with care.

Get in touch