Websites
engineered like
products.
I'm Sergio de la Garza — a senior full-stack & AI engineer with 20 years in production. I build, rescue, and operate websites and platforms for US companies — 200+ client sites, from custom WordPress builds to AI-powered data products.
Every claim on this page has a number attached.
20
Years in production
200+
Client sites shipped
100+
WordPress builds
13
Years agency-side, US
90+
Mobile PageSpeed, typical result
What I do
Five disciplines. One standard of delivery.
Every engagement ships with scoped milestones, upgrade-safe code, and documentation. Pick the lane that matches your problem.
WordPress & CMS
Custom themes and plugins built to survive a decade of core updates.
Full-Stack
Production web apps, from database to interface.
AI Consulting
AI that does something useful in production.
Performance
Guaranteed 90+ mobile PageSpeed — measured before and after.
Cloud & Data
Infrastructure and pipelines you can rebuild from the repo.
About
One engineer, start to finish.
I'm Sergio de la Garza — 20 years in production, 13 of them as the sole in-house engineer at a US digital marketing agency. Your project is scoped, built, and shipped by the same senior engineer who quoted it: no handoffs, no account-manager telephone game.
20
Years in production
200
+Client sites shipped
100
+WordPress builds
13
Years agency-side, US
Selected work
Shipped — and still running.
See all workOnRamp · B2B integration platform
AI & Data · OnRamp
OnRamp · B2B integration platform
9 FastAPI microservices, 6 named LangGraph agents, Temporal durable workflows. Live EDI and AS2 integrations with QVC and Tractor Supply.
View projectCalibrate BI Dashboard
AI & Data · Calibrate Network
Calibrate BI Dashboard
2.26M transactions and $7.79M revenue modeled over 18 SQL views. Big queries return in under 200ms.
View projectAgency flagship site
WordPress & CMS · US digital-marketing agency
Agency flagship site
Custom WordPress theme from scratch — no page builders. ACF modular layouts and custom post types. Ran 10+ years without a rebuild while marketing shipped landing pages with zero developer tickets.
View projectResults
Slow sites don't survive. I fix that.
KFB Law
49 → 95
A personal-injury law firm's site was losing mobile search visibility and paid-lead conversions to load time. Mobile PageSpeed Insights sat at 49, with Total Blocking Time at 1,160ms — the page was technically loaded but unusably slow to interact with. Previous attempts had been plugin-level and made things worse.
Pacific NW Capital
62 → 98
A finance company's marketing site scored 62 on mobile PageSpeed Insights, with a Largest Contentful Paint of 7.5 seconds and visible layout shifts as late-loading assets pushed content around. For a firm whose product is credibility, the slow, janky first impression was a direct business problem.
Estherian Clinic
54 → 93
A clinic's appointment-driven site was scoring 54 on mobile PageSpeed Insights, with a Largest Contentful Paint of 10.4 seconds — patients were waiting through a full page-weight download before they could even see the booking call to action.
The methodology is an audit, not a caching plugin.
Performance optimizationProcess
How an engagement runs.
The same four steps, whether it's a theme rescue or a data platform.
Scope
I start with the numbers: current scores, error logs, or a broken build. You get a written scope with milestones and a fixed price before work starts.
Spec
Requirements become a technical spec — data models, component structure, integration contracts. Nothing gets built on a verbal yes.
Build
Milestone-based delivery in a demo environment you can click through. Upgrade-safe code, no edits to core or parent themes.
Launch & operate
Staged deploys, rollback plans, and documentation written for the next developer. I stay on to monitor, update, and iterate — one product has run in production with paying customers since 2024.
Products & open source
I build and operate my own.
All productsFour shipped side products. One runs in production with paying customers.
citadevisa.com
Production SaaS monitoring US visa appointments across Mexico. Stripe billing, multi-role auth, live admin dashboard. Built solo.
QueryChat AI
AI-powered data chat with multi-DB abstraction and real-time LLM streaming.
What clients say
One quote. Thirteen years of these.
“Sergio is without a doubt the best developer I have ever worked with. As a demanding web company with demanding clientele, I have demanded fast working, versatile, and adaptable web developers that can work under stress. Sergio always came through above and beyond all expectations. I definitely would recommend him to any one.”
I worked with Sergio for over a year and would continue to do so had I not been pursuing some other opportunities in the interim. Sergio is a great guy, reliable and a brilliant programmer!
Olin Patterson
Web agency owner
More references on request — including 13 years of agency-side clients.
FAQ
Questions, answered.
Do you work with agencies?
Yes. I spent 13 years as in-house engineering for a US digital marketing agency and shipped 6 white-label theme systems under its account. Agencies get NDA-friendly workflows and clean handoffs.
Who will actually do the work?
I will. I'm a senior developer with 20 years in production and certifications from Microsoft and IBM — no handoffs to juniors. When a project needs more hands, I extend with vetted specialists under the same standards.
How do you guarantee 90+ PageSpeed scores?
It's rarely just a caching plugin. I audit the DOM, eliminate render-blocking JS and CSS, ship modern image formats, and restructure how the browser loads the page — then measure the result with you.
Can you rescue a legacy WordPress site?
Regularly. I'm fluent in every major page builder — Divi, Elementor, Avada, and the rest — and have restored sites from nothing but a SQL dump and a public_html zip.
What does an engagement cost?
Projects start with a written scope at a fixed price. Tell me what you're solving and I'll scope it within one business day — budget ranges are on the contact page.
Do you take retainers?
Yes — monitoring, updates, and iteration after launch are the norm, not the exception. One of my SaaS products has been in production since 2024.
Is there a minimum project size?
For full-stack or AI work, projects generally start around $5,000 — smaller builds are usually better served by a template or a junior freelancer, and I'll say so if that's the case. WordPress fixes and performance audits can start smaller. Not sure? Send it anyway — the budget-range question on the contact form helps me answer honestly and fast.
What time zones do you cover?
Remote, bilingual (English/Spanish), working US time zones.
Have a site to build — or a fire to put out?
Tell me what you're solving. I reply within one business day.
No sales call. If it's not a fit, I'll say so.