A senior product engineer for the stage after "it works."

I help founders, product leads, and small product teams move a working prototype or existing product toward an agreed dependable release with clearer ownership and visible verification.

I work as an independent product partner. That means I do more than complete isolated tickets: I help define the next owned outcome, connect product and system decisions within the agreed scope, and make the handoff or release state explicit.

Product judgment, full-stack delivery, and accountable use of AI.

My primary category is Senior Full-Stack Product Engineer. I bring at least nine years of production delivery across product interfaces, application systems, integrations, testing, and cloud infrastructure.

I use AI-assisted workflows to coordinate research, implementation, and review across the agreed technology scope. I remain accountable for product and system decisions, verification, the delivered work, and the limits of what the evidence supports. AI is part of the method, not the primary category and not a claim that every product needs an AI runtime.

What direct ownership looks like.

I work best when a founder or product lead has a meaningful product consequence, a working state to understand, and a next outcome that needs one accountable senior owner.

We make the scope and decision boundaries explicit. I connect the product and system decisions I own, show the evidence behind completion, and release or hand off the agreed state. The engagement keeps ownership inside and outside the scope visible.

A bounded specialist, lower-cost provider, agency, internal employee, or AI-assisted DIY approach may be the better fit when the work is well specified, already well led, easily verified, or requires continuous team capacity. The goal is fit, not provider theater.

Code editor showing full-stack product work

Established full-stack delivery, honestly scoped.

The strongest public evidence is a dated Upwork record, client feedback about how I work, and the approved Armonía product case.

As captured on 2026-09-04, Upwork showed 29 total jobs, 28 completed jobs, one job in progress, 15,309 hours, 100% Job Success, and Top Rated Plus. Client feedback supports autonomy, reliability, quality, communication, testing, UX judgment, maintainability, and launch contribution.

Those facts support full-stack production judgment and direct ownership. They do not establish nine years of AI-product work or repeated production agents, RAG, evaluations, regulated AI, or AI-built-app rescue outcomes.

Dated Upwork record

As captured on 2026-09-04: 29 total jobs, 28 completed jobs, one job in progress, 15,309 hours, 100% Job Success, and Top Rated Plus.

29

Total jobs

15,309

Total hours

100%

Job Success

Top Rated Plus

Upwork status

Just like the last time we engaged with him, Xavier helped us out reliably and efficiently. He specifically supported us in improving our unit and integration tests integrating emulators for our backend services into the test process.-- Johannes Stiehler

Xavier is a talented frontend developer, who supported our project for months and took our ideas from a google doc to an actual product/prototype. Xavier is fun to work with, a great team player and very accountable. We are a remote team, and Xavier just fit right into our team culture.-- Karan Dhingra

Xavier is a talented software engineer who took our React/Redux project from 0 to 100 in record time. Xavier was able to quickly and expertly solve every problem we came across throughout the development process, which has resulted in a stellar end product. He has an eye for design and UX that sped up development significantly.-- Jake Glass

Xavier was an invaluable part of our team, using his React expertise to bring pixel perfect screens to life as promised. Of all of the React developers we've worked with - on Upwork and otherwise - Xavier was one of the very top engineers with whom we've been lucky enough to have on our team.-- Alli McKee

Xavier is not a typical fly-by freelancer, his commitment to success of our project was amazing. Xavier's technical skills especially in React application development can be compared to a world class developer. His methodical approach to writing code resulted in a easily maintainable code that my company can continue to use it as an asset going forward. Xavier's work ethics is one of the best I have seen across all kinds of staffing models, he is very direct and gives honest feedback on ideas that he thinks will work or not work.-- Sanjay Mahadi

Xavier was an outstanding addition to the team. Easy to work with, great communication. We asked Xavier to help us with our complex Node.js web app working with React, Relay, and GraphQL. He ramped up on our application very quickly and immediately added value to the project... It was as if he had been a member of the team all along. Worked efficiently and followed development processes like a true professional. We would definitely hire Xavier again in the future-- Adam Tratt

Clear communication starts before implementation.

We align on the current product state, the next owned outcome, decision boundaries, and what evidence will count as complete.

If your working product needs clearer ownership for its next state, schedule an initial fit conversation or review selected work first.

Product decisions mapped before implementation

Does your working product need clearer ownership for its next state?

Bring the current product state, the outcome that matters next, and where ownership is unclear. An initial conversation will establish whether direct senior ownership fits the work.

Schedule a meeting See selected work