I build from the ground up, database to interface

Software engineer in San Diego with four years across startups and enterprise, currently leading architecture on a robotics platform running in production. Available for freelance work — a whole product, or extra hands on your team.

Start a project See selected work

Based: San Diego, CA
Experience: 4+ years
Languages: English · Spanish
Focus: Backend · Full-stack · Mobile

Selected work

Things I've built

Platforms, client apps and websites that made it to production and stayed there.

2026 — NowTechforce Robotics
Lead software engineer
- FastAPI
- React
- PostgreSQL
- Docker
- WebSockets
Robotics-as-a-Service platform
Architected and led development of the platform behind an autonomous robot fleet — admin and customer portals covering business setup, robot provisioning, fleet configuration and linen and waste collection missions, plus the communication layer between remote services and PLC hardware. It is one of several projects I have led there, alongside infrastructure work for other product lines.
Live across hospitality, gaming and education customers, running 25 robots and 30+ missions a day for 20+ daily users.
The trade-off
The primary intention was creating a monolith. The product lines that would define service boundaries did not exist yet, so I took a later refactor over guessing wrong early, and split to microservices once the boundaries were real. Self-hosting was the other call: we wanted the hardware and network under our own control, and the price is that reverse proxies, TLS, redundancy and environment management are mine to run rather than a managed service's.
2024 — Jan 2026Exact Sciences
Software engineer
- Java
- Spring Boot
- Hibernate
- Selenium
- GitLab CI
Backend services and test automation
Backend services in Java and Spring Boot covering business logic, role-based authorization, data processing, XML report updates and automated email delivery. Co-built Selenium and JUnit automation frameworks from scratch and wired them into GitLab CI/CD.
30+ automated test cases across four repositories cut manual QA effort by around 30% and raised release confidence for a 10-engineer team.
The trade-off
We built the framework from scratch rather than adopting one off the shelf. It cost setup time, but it fit four repositories an existing framework would have fought. I also took end-to-end coverage over fast unit tests, and breadth over depth early — slower CI in exchange for the kind of confidence that actually lets a team release.
2026
Sole developer
- Flutter
- Riverpod
- Supabase
- Scryfall API
- Cloudflare Pages
Board Wipe — a tabletop for paper Magic
Visit site
A shared virtual tabletop for Magic: The Gathering Commander, built for groups playing over voice chat. Deliberately not a rules engine — players tap, untap and move their own cards, and the app's only job is keeping every phone in sync. Card data comes live from Scryfall. A frontend engineer I work with designed it in Figma and I built all of it.
Live and actually used — people have played full games on it rather than just seen it demoed.
The trade-off
Realtime runs on Supabase Broadcast and Presence rather than database change streams, with no tables behind it at all. That keeps the table fast and cheap to sync and costs me durability: game state lives only as long as the session. Moving from a native app to Flutter web was the other call — it means no install and iPhone support without owning a Mac, and it keeps the whole thing off the app stores, where a rights-holder takedown could remove a build I would have no way to restore.
2025Distridav
Freelance engineer
- Next.js
- TypeScript
- Figma
Industrial distributor website
Visit site
Designed, built and deployed a production Next.js site from Figma designs for an industrial supplies distributor in Tijuana, replacing a legacy Google Sites setup with a responsive Spanish-language site the team could actually grow into.
Enquiries through the site went up after launch, on semantic HTML, SEO metadata and responsive layouts the previous setup never had.
The trade-off
A page builder would have let them edit the site themselves. I built it in Next.js instead, trading that convenience for the load speed and search visibility the old Google Sites setup could not reach.
2022 — 2024CBLUNA
Software engineer
- Flutter
- Firebase
- REST APIs
Client web and mobile apps
Built and maintained more than five web and mobile applications across six client engagements, including customer-facing platforms for a US rural telecommunications provider covering payments and telephone number porting, plus Flutter apps with camera integration, authentication, push notifications, real-time updates, offline persistence and scheduling.
Grew from feature work into end-to-end ownership of delivery, shipping for domestic and international clients alongside a team of seven engineers.
The trade-off
Flutter and Firebase over native apps and a custom backend. Across six client projects that meant one codebase and a backend nobody had to run, paid for with some platform fidelity and a dependency we did not control — the right call when each client needed shipping, not bespoke infrastructure.
Client branding redacted
2024HackMTY
AI integration & frontend
- Next.js
- OpenAI API
- Django
CapyCode — AI technical interviews
Timed coding problems solved in a browser editor and reviewed automatically: a plain-language verdict plus the specific logic faults, like an early return that rejects valid input. Built for candidates practising interviews, and for companies to run the review side without an engineer having to sit in.
Placed at HackMTY. I built the OpenAI wrapper and the response handling that turns a raw model reply into consistent, structured review, and worked on the frontend.
The trade-off
The OpenAI API over a self-hosted model — better review quality immediately, paid for in per-call spend and no control over the model underneath. The harder constraint was forcing structured output instead of free-form replies: less expressive, but a review you can render and compare rather than a paragraph that changes shape on every run.
2024BioMedTech, ITJ
Mobile engineer
- Flutter
- React
- Socket.IO
- Django
- Supabase
Lifeline — ambulance dispatch
An Uber-style dispatch application for ambulances. A patient shares their location, connected ambulances receive it in real time over websockets, and the crew tracks it on a live map alongside vehicle and driver details.
I owned the mobile side end to end, including the websocket layer that kept it in sync with the web dispatch view.
The trade-off
The mobile backend went on Supabase rather than extending the Django web app. That split the system in two, but it let me move without waiting on the web team — worth it when the whole build had to land inside a hackathon.
What I'd change
The two-backend split was right for a hackathon and wrong for anything meant to last. Building for real, I would put the mobile app on the same Django backend and accept the slower start.

Services

How I can help

Clear scope, direct communication, working software at the end of it.

01Clients

Web app
Mobile app
Admin portal
Public site
Operator console

02Edge

Reverse proxy
TLS
Rate limiting
Caching
Load balancing
CDN

03Application

REST API
WebSocket gateway
Auth & roles
Background jobs
Scheduled tasks
Notifications
Audit logging

04Data & devices

PostgreSQL
Object storage
Hardware layer
Third-party APIs
Backups

01
Product & MVP builds
You have an idea and a deadline. I take it from spec to a working product in front of real users — interface, backend, database and deployment.
02
Design and build
Need the design as well as the build? I bring in designers I've worked with — real people making decisions in Figma, not generated layouts — and I implement exactly what they hand over.
03
Backend & architecture
APIs, data models and system design that survive growth. FastAPI, Spring Boot and PostgreSQL schemas that still make sense a year later.
04
Web applications
Next.js and React builds from Figma files or a rough sketch. Fast, responsive, accessible, and readable enough that the next developer isn't lost.
05
Mobile apps
Cross-platform Flutter apps from one codebase — authentication, push notifications, offline persistence, camera and real-time sync.
06
Deployment & infrastructure
Docker, CI/CD pipelines, reverse proxies, TLS and environment management. Cloud or on-premises, with a test environment that mirrors production.
07
Team extension
Extra engineering for teams that need it. I've led sprints, reviewed pull requests and mentored engineers — I work well with designers and don't need hand-holding.

Contact

Tell me what you're building

Give me a rough idea of the project, the timeline and the budget you have in mind. I reply to everything within a working day.

Prefer email? Write to leonardoomercado2@gmail.com

I build from the ground up, database to interface

Things I've built

Robotics-as-a-Service platform

Backend services and test automation

Board Wipe — a tabletop for paper Magic

Industrial distributor website

Client web and mobile apps

CapyCode — AI technical interviews

Lifeline — ambulance dispatch

How I can help

Product & MVP builds

Design and build

Backend & architecture

Web applications

Mobile apps

Deployment & infrastructure

Team extension

Tell me what you're building