Software problems solved — from idea to production.
I'm Pablo, a senior full-stack engineer — backend-first — with 10+ years building production systems across very different industries. From the database to the screen your users see: whether you need something built from scratch, fixed, sped up or rescued, I take it end to end. Clear scope, written proposal, working in your timezone.
What are you looking for?
Build your idea from scratch
From a blank page to a working product: architecture, backend, a simple front end and deploys. Built to grow, not to be thrown away.
Built and run a SaaS on my own, live with paying subscribers; shipped a real-time messaging MVP for a NYC startup.
Tell me about it →Web apps and dashboards
Admin panels, customer portals, dashboards and checkout screens in React / Next.js, built on a solid component library and connected to a backend that holds up.
Rebuilt a 179-page web app in Next.js + React; built a hotel KPI dashboard; checkout UIs with Apple Pay, Google Pay, PayPal and Mercado Pago.
Tell me about it →A mobile app
iOS and Android from one codebase with React Native / Expo, sharing the backend and data with your web app.
Replaced a legacy Cordova app with a React Native / Expo app: role-based navigation, signatures, photo and audio reports, QR scanning.
Tell me about it →Payments that work
Add online payments — from the checkout screen and wallet buttons to the backend and webhooks — fix a checkout that fails or declines good cards, or set up subscriptions.
Brought card approval rates back above 90% at a global e-commerce company; 10+ payment providers integrated.
Tell me about it →Rescue or migrate an old system
Outdated PHP / Laravel, no security patches, nobody dares to touch it. Upgraded in place or rebuilt in parallel.
Rebuilt a legacy SaaS at full parity in 5 weeks; migrated a PHP 5.6 codebase to PHP 8.
Tell me about it →Fix or improve your database
Reports with wrong numbers, slow queries, messy data, business logic buried in stored procedures. MySQL, PostgreSQL, SQL Server, MongoDB.
Found a date bug that under-reported accident metrics 20×; worked with 100+ table schemas full of stored procedures.
Tell me about it →Make it faster
Slow pages, a slow checkout, timeouts under load. I measure first, then fix what actually matters.
Cut landing and checkout load times by about half for a NYC startup.
Tell me about it →Connect your systems
Third-party APIs, webhooks and data syncs between platforms that should talk to each other and don't.
Synced 50,000+ listings daily across 5 real estate portals; built hotel accounting and payroll data pipelines.
Tell me about it →Add AI to your product
Assistants, data extraction from documents and spreadsheets, automatic analysis — with sensible costs and a fallback when a provider fails.
In-app assistant with a Claude → OpenAI → Gemini fallback; AI onboarding that drafts data from customer spreadsheets.
Tell me about it →Deploys, cloud and monitoring
Automated deploys, Docker, AWS, backups, audit logs and error tracking, so problems show up before your customers report them.
Set up CI/CD where there was none, twice; moved user files from server disks to S3.
Tell me about it →What I don't do: visual or brand design, native Swift / Kotlin apps, or store setups on Shopify, Wix and similar builders.
Problems I've already solved
Legacy SaaS at full parity in 5 weeks, not 3 months
A Laravel 5.7 system without security patches for years, 111 tables and a Cordova app. I rebuilt it on a modern TypeScript stack in parallel with the old system: 419 endpoints and 37/37 reports at full parity, plus a new mobile app — and found a bug that was under-reporting accident metrics 20×.
Card approval rates back above 90%
Approvals in key international markets had collapsed. I implemented 3DS2 correctly, enriched the data sent to card issuers and fixed recurring-payment flags. Hundreds of thousands of dollars in legitimate sales stopped being declined.
PHP 5.6 → PHP 8, checkout ~50% faster
Migrated a legacy codebase to PHP 8 + Laravel 9 and replaced manual deploys with CI/CD. Landing and checkout load times dropped by about half.
10+ payment providers in one checkout
Cards, Apple Pay, Google Pay, buy-now-pay-later, bank payments and local methods across North America, Europe and Asia, unified behind a single payment layer.
From idea to paying customers, on my own
Designed, built and run an electronic invoicing SaaS: multi-tenant backend, tax-authority integration, subscriptions and an in-app AI assistant. Live with paying subscribers.
How it works
Tell me what is going on
Two minutes with the form below. No sales pitch.
Short call
A free 20-minute call to understand your setup and goals.
Written proposal in 48h
Scope, price and timeline in writing. For larger or undocumented systems, a short paid diagnostic comes first.
Build, test, go live
Tested before anything reaches your customers, then launched, with a short handoff doc.
What you get
- A senior engineer, directly — no agency layers or account managers.
- Clear written English, async-friendly, 1–2 hours ahead of US Eastern.
- Your business keeps running: changes ship in parallel or behind carefully planned cutovers.
- Card data never touches your server: I use provider-hosted fields and checkouts to keep your PCI scope minimal.
- The code and the accounts are yours from day one.
FAQ
What platforms do you work with?
Custom-built websites, apps and APIs — mainly PHP / Laravel and Node.js / TypeScript, with MySQL, PostgreSQL or MongoDB.
I use Shopify, Wix or Squarespace. Do I need you?
Probably not — their built-in payments are usually the right answer. I help products with their own checkout or backend: SaaS, marketplaces, custom-built stores and apps.
My system is old and undocumented. Is that a problem?
No — that is the usual starting point. I read the existing code and database, document what it really does, and keep that behavior while the stack changes.
How much does it cost?
After the call you get a written proposal with scope and price. Well-defined work gets a fixed price; larger or undocumented systems start with a short paid diagnostic so the estimate is real. Most payment integrations take days, not months; rebuilds are scoped in phases so you see progress early.
How do contracts and payment work?
Written scope, invoice in USD, a deposit to start and the rest on delivery. Happy to sign an NDA.
What size of projects do you take?
Well-scoped projects with part-time dedication: an integration, a fix, an upgrade, or a rebuild split into phases. I am not available as a full-time contractor or to join a team indefinitely.
Are you available right now?
I take a limited number of projects at a time, so I can give each one proper attention. Send the form and I will tell you honestly when I can start.
Tell me about your project
I reply within one business day.