Javier
Costa Rosa

Tech Lead | Product Architecture | AI & Distributed Systems

I design and evolve product systems under real constraints — balancing architecture, delivery, reliability, and long-term maintainability.

📍 Greater Valencia, Spain · Architecture · Backend Systems · AI in Production
About

Building and evolving product systems under real constraints.

I'm a Tech Lead with experience designing and evolving backend systems and digital products across healthcare, browser products, and web-scale data workflows. My work sits at the intersection of product architecture, technical direction, and reliable delivery. I'm especially interested in systems that need to balance product constraints, operational simplicity, and long-term evolution.

Architecture from requirements
Translating product constraints and domain needs into clear system boundaries and technical direction.
🏗️
Systems that hold up
Reliability, maintainability, and operational clarity — not just for the first release.
🤖
AI where it reduces friction
I focus on AI where it unlocks real capability or removes operational overhead — not as a feature for its own sake.
📐
Technical ownership
I work best where technical decisions directly shape what the product becomes.
How I think about architecture
📐
Clear boundaries beat clever abstractions.
Well-defined domain boundaries make systems easier to reason about, evolve, and hand off — without requiring everyone to understand everything.
🔒
Reliability matters from the first version.
Retrofitting reliability is expensive. The decisions that matter most — fault tolerance, observability, failure handling — are easier to get right early.
⚙️
Product constraints are architecture inputs, not annoyances.
Delivery pressure, team size, operational limits — these shape what's actually viable. Good architecture works within constraints, not around them.
🤖
AI only belongs where it reduces friction or unlocks capability.
I'm skeptical of AI features that exist to check a box. The bar is simple: does it make something meaningfully better, or does it add complexity for nothing?
What I look for

I'm especially interested in product environments where architecture is shaped by real constraints: evolving requirements, operational complexity, reliability, and long-term maintainability.

Experience
Blue Trail Software

Tech Lead – AI Product Reliability & Architecture

Aug 2025 – Present

Leading the technical evolution of a high-usage web crawling product used daily by thousands of customers. Focused on architecture, reliability, observability, execution consistency, and AI-assisted engineering workflows in a lean product team.

ArchitectureAI/LLMsObservabilityReliability

Tech Lead – Product Engineering & Browser Extension

Nov 2024 – Aug 2025

Led the evolution of a browser extension product for automated consent management. Defined architecture under strong technical constraints, guided delivery and engineering quality, and translated business needs into a sustainable product direction.

Team LeadBrowser ExtensionArchitecture

Tech Lead & Solutions Architect

Apr 2023 – Oct 2024

Owned a healthcare automation platform end-to-end, from requirements and client interaction to architecture, AWS infrastructure, data modeling, and delivery. Acted as the main technical counterpart for stakeholders and led engineering execution around security, scalability, and maintainability.

AWSHealthcareSolutions Architecture

Senior Full Stack Engineer

Mar 2021 – Apr 2023

Contributed to the evolution of a monolithic platform into a microservices architecture across roughly 10 services. Improved modularity, modernized the backend stack with TypeScript and NestJS, and helped raise engineering standards through shared libraries, mentoring, and internal tech talks.

Node.jsTypeScriptNestJSMicroservices
ITI – Instituto Tecnológico de Informática

Full Stack Engineer – R&D

Feb 2018 – Mar 2021

Worked on research and innovation projects across AI, IoT, and blockchain. Built internal tools and web applications across frontend and backend, applying solid engineering practices in exploratory environments.

R&DAIIoTBlockchainPython
F1-CONNECTING

IT Support Intern

Jul 2017 – Dec 2017

Provided IT support for retail POS systems and automated repetitive support tasks with scripts.

IT SupportAutomation
Selected work

Healthcare workflow automation

Tech Lead & Solutions Architect · Blue Trail Software
Challenge

A manual, spreadsheet-heavy healthcare operations workflow that was fragile, error-prone, and couldn't scale.

Constraint

End-to-end ownership with no existing platform foundation, strong compliance and data security requirements, direct client dependency.

Decision

Designed a purpose-built platform from scratch — full technical ownership across requirements, AWS infrastructure, data modeling, and delivery. Kept the architecture simple enough to be maintainable by a small team.

Outcome

Eliminated a category of operational errors and replaced a fragile process with a system the client could actually scale.

HealthcareAWSSystem Design

Consent management browser extension

Tech Lead · Blue Trail Software
Challenge

Evolving a browser extension for automated consent management under strict and shifting platform constraints.

Constraint

Browser extension environment imposes hard limits: CSP rules, limited storage, cross-browser compatibility, no access to native APIs. Short-term delivery pressure alongside long-term product evolution.

Decision

Defined a maintainable architecture with clear separation of concerns. Prioritized extension longevity over feature velocity — keeping the core stable while enabling product iteration on top.

Outcome

Team of 5 delivered a sustainable product direction within tight constraints, with architecture that could absorb platform changes without full rewrites.

Browser ExtensionTeam LeadArchitecture

AI in a high-usage crawling product

Tech Lead · Blue Trail Software
Challenge

Integrating AI meaningfully into a production crawling system used daily by thousands of customers — without compromising reliability or adding operational overhead.

Constraint

Lean team, high usage volume, need for consistency and observability in AI-driven flows. AI features had to be reliable, not experimental.

Decision

Introduced LLM-based workflows and RAG systems designed around real user flows and operational constraints. Also applied AI-assisted engineering to reduce repetitive internal work.

Outcome

Enabled AI-powered product capabilities with production-grade reliability, and improved internal delivery throughput in a lean team.

LLM PipelinesRAGAI Product Features
Core strengths
Product Architecture
System design, domain boundaries, technical direction, stakeholder alignment
System DesignDomain BoundariesTechnical DirectionStakeholder AlignmentTechnical RoadmapArchitecture Trade-offs
Distributed Systems & Reliability
Backend systems, API design, observability, fault tolerance, system evolution
Node.jsTypeScriptPythonNestJSAPI DesignMicroservicesObservabilityFault ToleranceSystem EvolutionAWSDocker
AI in Production
LLM workflows, RAG systems, AI-enabled product features, practical automation
LLM WorkflowsRAG SystemsAI Product FeaturesPractical AutomationOpenAI APILangChain
Education
2018 – 2020
Universitat Politècnica de València (UPV)
Master's Degree · Software Engineering, Formal Methods and Information Systems
Thesis: Design and development of a Java program slicer based on the System Dependence Graph
2014 – 2018
Universitat Politècnica de València (UPV)
Bachelor's Degree · Informatics Engineering
Contact

Open to Staff-level product architecture and engineering leadership conversations

I'm most interested in roles where architecture, product constraints, and system evolution matter more than hype.