João Massan
Senior Software Engineer
Java · 20+ years · eBay · Distributed Systems · Cloud · AI
Brazil · Remote · Available for US time-zone contractor engagements20 years building Java systems across e-commerce, telecom, agribusiness, and marketplace platforms. Currently at eBay, working on data infrastructure and AI tooling at scale.
20+
Years of Experience8
Companies and Clients6
CertificationsAbout
Java developer with 20 years of experience across e-commerce, telecom, agribusiness, and marketplace platforms. I have worked as a sole engineer on greenfield systems, as a tech lead on large teams, and currently as a senior engineer embedded in eBay's SEO organization.
My core is Java and Spring Boot, but over 20 years the stack gets broader: Kubernetes, AWS, Python, data pipelines, Flink, and more recently AI/LLM tooling in production. I have always preferred working on systems with real complexity over straightforward CRUD.
Based in Brazil, working remotely. Available for US-based remote roles as a contractor or through platforms like Deel.
20+
Years of Experience8
Companies & Clients6
Certifications5+
IndustriesExperience
Software Engineer
eBay Inc · Remote contractor via Avenue Code
Owned production streaming infrastructure for SEO data ingestion — stabilized Flink jobs under load (tens of thousands of messages per second), drove incident response, checkpoint tuning, and operational documentation across the full pipeline
Designed and delivered graph-scale PageRank computation for eBay's SEO interlinking strategy — source dataset exceeding one billion rows, resulting graphs spanning hundreds of millions of vertices and tens of billions of edges, with production runs completing in under one hour
Built eBay's first production AI/LLM tooling layer using the Model Context Protocol — from proof-of-concept through security review, pentest clearance, and deployment across four environments; the platform exposes structured SEO intelligence to LLM clients with enforced operational guardrails
Solutions Architect & Lead Engineer
Farmbits · Hybrid — Londrina, PR, Brazil
Architected and built the full cloud-native platform on AWS EKS from day one — sole engineer across backend (Java/Spring Boot), web (Vue.js), and mobile (Flutter/Dart)
Designed offline-first Flutter mobile app replicating SAP pricing logic entirely on-device, enabling field consultants to generate quotes in zero-connectivity rural environments
Led technical hiring, engineering culture, and architectural direction — building the team from the ground up and setting technical standards for the client's digital innovation subsidiary
Remote Java Analyst
Navita · Remote
Delivered feature additions, bug fixes, and performance improvements for Connect Platform across Spring Boot backend and Angular frontend
Contributed to AngularJS → Angular 7 frontend migration
Operated in a fully remote, async-first engineering team — years before remote-first became industry standard
Java Tech Lead
X-Brain Desenvolvimento de Sistemas · Londrina, PR, Brazil
Led architecture migration of NET/Claro's national sales platform from Java EE monolith to Spring Boot microservices + ReactJS
Designed and built a VoIP-based predictive dialer eliminating manual-dialing wait time, measurably increasing operator throughput
Integrated IBM Watson NLP chatbots via Node.js — among the earliest production chatbot deployments for a commercial sales channel in Brazil
IT Specialist Level III
Infracommerce Negócios · Londrina - PR / São Paulo - SP, Brazil
Redesigned the platform pricing model from per-product to per-SKU, unlocking the multi-seller marketplace architecture
Evolved platform from single-tenant e-commerce to full multi-tenant marketplace, serving major Brazilian retailers
Delivered third-party integrations (logistics, payment, catalog) via JAX-RS and JAX-WS
Java Expert Level III
Accurate Software · Londrina - PR / São Paulo - SP, Brazil
Designed and built a WYSIWYG dynamic i18n engine for Carrefour's e-commerce platform — runtime language switching with zero redeployment
Delivered multilingual support for PT, EN, and FR; content managers could translate the storefront without engineering involvement
Development Manager / Java Software Architect
BRCont & IBPT · Londrina/Curitiba, PR, Brazil
Architected BRCont SaaS from scratch; company acquired by IBPT in under 12 months of operation
Contributed to 'Lupa no Imposto' — software now embedded in every Brazilian fiscal receipt displaying estimated tax percentages
Led development team through post-acquisition integration and platform evolution at IBPT
Analyst / Developer Java
X-Brain Desenvolvimento de Sistemas · Londrina, PR, Brazil
Designed and built NET's national Door-to-Door sales platform in Java/JBoss Seam from scratch — replaced a legacy PHP system and rolled out across ~50 national franchises
Delivered what was likely one of the first real-time GPS tracking systems for a large field sales force in Brazil, running on Nokia E71 devices
Notable Projects
PageRank at Marketplace Scale
Designed the architecture and data products for PageRank computation over the full crawler dataset. Built from design spike to production execution.
340B+ graph connections modeled. Over one billion source rows. Production runs completing in under one hour.Production MCP Service
Built the first MCP service at eBay from proof of concept through security and pentest review to multi-environment production deployment.
Deployed across four environments with enforced query guardrails protecting production resources.Cloud-Native Platform from Zero
Architected the full cloud-native platform on AWS EKS from day one as sole engineer. Delivered backend services in Java, a web portal in Vue.js, and an offline-first mobile app in Flutter for field consultants working in areas with no phone signal.
Thousands of agribusiness customers. Full AWS EKS cluster in production, operated without dedicated DevOps support.National Door-to-Door Sales Platform
Rewrote the platform in Java from the ground up. Designed a multi-franchise deployment pipeline and added real-time GPS tracking for field sales reps using Nokia E71 devices.
Deployed across 50 national franchises. One of the first real-time GPS field-tracking systems for a large sales force in Brazil.Large-Scale E-commerce Marketplace
Redesigned the pricing model from per-product to per-SKU, which unlocked the multi-seller architecture. Evolved the platform to support multiple major Brazilian retailers simultaneously.
Platform evolved into one of Brazil's first large-scale online marketplaces, later known as Extra.com.br.Technical Expertise
Core
Primary stack, applied daily in production systemsAlso Experienced With
Regularly applied in professional contextsCertifications
Certified Kubernetes Application Developer (CKAD)
Professional Scrum Master (PSM I)
Oracle Java Persistence API Developer Certified Expert
Oracle Java EE Enterprise JavaBeans Developer Certified
Oracle Certified Web Component Developer
Oracle Certified Java Programmer
Get In Touch
Feel free to reach out about a role, a project, or just a conversation about distributed systems or Java.
Connect on LinkedInJoão Massan · Senior Software Engineer · joaomassan.devJoão Massan
Senior Software Engineer
Professional Summary
Senior Backend / Platform Engineer and IT Consultant with 20+ years designing and operating production systems at scale — Java, Spring Boot, Rust, Python, Node.js, Kubernetes, AWS. Currently embedded at eBay's SEO engineering organization: owning streaming infrastructure processing tens of thousands of messages per second, delivering graph-scale computation across billions of edges for SEO intelligence, and shipping eBay's first production AI/LLM tooling layer using the Model Context Protocol. Proven technical leader across distributed systems, cloud-native architecture, and greenfield platform design. Open to IT consulting engagements, Senior/Staff direct-hire, and contract opportunities at US-based companies — available as a foreign contractor, via LLC, or via Deel.
Work Experience
- Owned production streaming infrastructure for SEO data ingestion — stabilized Flink jobs under load (tens of thousands of messages per second), drove incident response, checkpoint tuning, and operational documentation across the full pipeline
- Designed and delivered graph-scale PageRank computation for eBay's SEO interlinking strategy — source dataset exceeding one billion rows, resulting graphs spanning hundreds of millions of vertices and tens of billions of edges, with production runs completing in under one hour
- Built eBay's first production AI/LLM tooling layer using the Model Context Protocol — from proof-of-concept through security review, pentest clearance, and deployment across four environments; the platform exposes structured SEO intelligence to LLM clients with enforced operational guardrails
- Created an internal developer productivity platform covering 20+ services in under a day, then drove it through distributed cache onboarding, staging/production hardening, and architectural improvements to data freshness
- Contributed to platform security modernization (auth migration across multiple services), observability uplift (production alerts and real-time metrics), and throughput protection design for high-volume image processing pipelines
- Architected and built the full cloud-native platform on AWS EKS from day one — sole engineer across backend (Java/Spring Boot), web (Vue.js), and mobile (Flutter/Dart)
- Designed offline-first Flutter mobile app replicating SAP pricing logic entirely on-device, enabling field consultants to generate quotes in zero-connectivity rural environments
- Led technical hiring, engineering culture, and architectural direction — building the team from the ground up and setting technical standards for the client's digital innovation subsidiary
- Owned and operated the full AWS EKS cluster, GitLab CI/CD, and container infrastructure in production — with no dedicated DevOps or SRE support
- Shipped Flutter to production before the framework's own 1.0 production-readiness recommendation — serving thousands of agribusiness customers
- Delivered feature additions, bug fixes, and performance improvements for Connect Platform across Spring Boot backend and Angular frontend
- Contributed to AngularJS → Angular 7 frontend migration
- Operated in a fully remote, async-first engineering team — years before remote-first became industry standard
- Led architecture migration of NET/Claro's national sales platform from Java EE monolith to Spring Boot microservices + ReactJS
- Designed and built a VoIP-based predictive dialer eliminating manual-dialing wait time, measurably increasing operator throughput
- Integrated IBM Watson NLP chatbots via Node.js — among the earliest production chatbot deployments for a commercial sales channel in Brazil
- Led cross-functional team through full-stack modernization: backend, ReactJS + Redux frontend, messaging (RabbitMQ), and MongoDB
- Redesigned the platform pricing model from per-product to per-SKU, unlocking the multi-seller marketplace architecture
- Evolved platform from single-tenant e-commerce to full multi-tenant marketplace, serving major Brazilian retailers
- Delivered third-party integrations (logistics, payment, catalog) via JAX-RS and JAX-WS
- Designed and built a WYSIWYG dynamic i18n engine for Carrefour's e-commerce platform — runtime language switching with zero redeployment
- Delivered multilingual support for PT, EN, and FR; content managers could translate the storefront without engineering involvement
- Architected BRCont SaaS from scratch; company acquired by IBPT in under 12 months of operation
- Contributed to 'Lupa no Imposto' — software now embedded in every Brazilian fiscal receipt displaying estimated tax percentages
- Led development team through post-acquisition integration and platform evolution at IBPT
- Designed and built NET's national Door-to-Door sales platform in Java/JBoss Seam from scratch — replaced a legacy PHP system and rolled out across ~50 national franchises
- Delivered what was likely one of the first real-time GPS tracking systems for a large field sales force in Brazil, running on Nokia E71 devices
Technical Skills
Certifications
Education