Javier Costa

Software engineer working across product, architecture and complex backend systems.

Valencia, Spain

What I do

Product architecture

Turn ambiguous requirements into technical direction, clear boundaries and delivery plans.

Backend systems

Design and evolve APIs, services and data flows that remain understandable as products grow.

Reliability

Improve observability, failure handling and the parts of a system that cause trouble in production.

Practical AI

Use LLMs and automation when they remove real work or unlock a useful product capability.

Focus
Product architecture, backend systems, reliability, practical AI
Technologies
TypeScript, NestJS, Node.js, Python, Angular, Vue, AWS, Docker
Engineering
Service architecture, APIs, observability, fault tolerance, data modelling, clean architecture

Selected work

Healthcare automation platform

Product architecture · Technical leadership

A healthcare operations team relied on spreadsheets and email for a business-critical workflow. The key was turning that informal process into a product with clear data, architectural and operational boundaries that could evolve safely.

Browser extension evolution

Architecture · Reverse engineering

A consent-management browser extension had to evolve under CSP, storage and cross-browser constraints. The key was separating product architecture from platform limitations so the system could keep changing without stalling delivery.

Web crawling reliability

Reliability · Backend systems

Customer issues in a high-usage crawling product often came from inconsistent execution and limited observability rather than isolated bugs. The focus became making failures visible and execution predictable enough for the product to evolve safely.

Experience

Blue Trail Software

Mar 2021 — Present

Tech Lead — Product Reliability & Architecture

Aug 2025 — Present

Leading the technical evolution of a web crawling product used daily by thousands of customers.

  • Improved reliability and reduced customer-reported issues through changes to architecture, observability, fault tolerance and execution consistency.
  • Expanded product capabilities while maintaining stability and delivery pace.
  • Introduced AI-assisted engineering workflows to improve delivery speed and long-term maintainability in a lean team.

Tech Lead — Product Engineering & Browser Extension

Nov 2024 — Aug 2025

Led a five-person team evolving a consent-management browser extension into a more robust product prepared for cross-browser expansion.

  • Defined an architecture that balanced platform constraints, delivery speed and long-term maintainability.
  • Worked with stakeholders to turn ambiguous business needs into clear technical direction and sustainable product decisions.

Tech Lead & Solutions Architect

Apr 2023 — Oct 2024

Designed and developed a healthcare automation platform that replaced spreadsheet- and email-based operational workflows.

  • Owned system architecture, AWS infrastructure, data modelling and technology decisions end to end.
  • Acted as the main technical counterpart for stakeholders and led the development team through delivery.

Senior Full Stack Engineer

Mar 2021 — Apr 2023

Contributed to the evolution of a monolithic platform into roughly ten services within a cross-functional engineering team.

  • Introduced TypeScript and NestJS to standardize backend development and built shared libraries that reduced duplication across projects.
  • Mentored junior engineers and launched weekly Tech Talks to strengthen knowledge sharing and engineering practices.

ITI — Instituto Tecnológico de Informática

Feb 2018 — Mar 2021

Full Stack Engineer — R&D

Developed web applications and technical tools for national and European R&D projects across AI, IoT and blockchain.

  • Worked across frontend and backend with Node.js, Python, Angular and Vue.
  • Applied clean architecture practices and Docker-based workflows in projects with evolving requirements and experimental scope.

Education

Universitat Politècnica de València

MSc in Software Engineering, Formal Methods and Information Systems

2018 — 2020

Universitat Politècnica de València

BSc in Informatics Engineering

2014 — 2018

Beyond work

Based in Valencia.
Usually somewhere around a piano
or underwater.