Lucas Antonio Ramos Sartori
Senior Ruby on Rails Engineer | Backend Architecture | PostgreSQL | Performance & Reliability
Senior Rails/backend engineer with 8+ years stabilizing and scaling mature SaaS systems — reliability, performance, test coverage, architecture, and production safety. I work with U.S.-based companies remotely from Brazil. Recent work includes event-driven search/indexing, legacy modernization, and AI workflows where they cut cost and latency.
Professional Experience
Senior Backend Engineer
Ballast Lane Applications · Remote · USA · Sep 2024 – Present
Backend engineer across multiple client products — event-driven systems, legacy modernization, and AI-driven workflows.
- Integrated business management platform for service providers.
- Built ElasticSearch + Karafka event-driven indexing pipeline, reducing database load and improving search performance.
- Implemented RSpec CI pipelines with 80%+ minimum coverage (most repos above 90%).
- Large-scale event and restaurant management platform.
- Redesigned prompts from 4k+ lines to ~450 using modular architecture — 60% Gemini cost reduction with better results.
- Redesigned duplication detection service: timeouts dropped from 4–20+ min down to 1–4 min.
- Applied prompt engineering and generative AI for reliable automation workflows.
- 10+ year multi-tenant legacy system.
- Designed REST APIs and owned backend integrations (internal + third-party).
- Created team CI enabling RSpec adoption — coverage grew to 50%+.
- Fixed performance and security issues: N+1, mass assignment, SQL injection.
Senior Software Engineer
FullStack Labs (NoFraud) · Remote · USA · Nov 2021 – Mar 2024
- High-volume e-commerce fraud detection platform.
- Rebuilt merchant dashboards, reporting systems, and document upload workflows.
- Integrated Brakeman and fixed security vulnerabilities.
Key Achievements
- Led dashboard rebuild.
- Increased test coverage from 2% to 40%+.
- Built integrations with BigCommerce and Adobe Commerce.
- Fixed N+1 queries, mass assignment, and SQL injection vulnerabilities.
Senior Software Engineer / Tech Lead
Grupo EUAX · Remote · Brazil · Dec 2020 – Nov 2021
- Led development of Twygo, a 10+ year online education platform.
- Ruby on Rails specialist and technical reference for a team of 4.
- Balanced feature delivery with refactoring and legacy system stability.
Key Achievements
- Resolved N+1 queries, mass assignment, and SQL injection across the codebase.
Fullstack Developer
Lets · Hybrid · Brazil · Apr 2019 – Nov 2020
- Delivered projects for startups, NGOs, and enterprises using Rails, Angular, Vue, and Node.js.
- Built SPAs, REST APIs, and mobile apps (Flutter, NativeScript, Kotlin).
Android Developer
Stape Music · Remote · Sep 2018 – Apr 2019
- Kotlin music streaming app — features, bug fixes, and musician monetization workflows.
Fullstack Developer
Teorema Sistemas · Guarapuava · Brazil · Jun 2017 – Sep 2018
- ERP system with Spring Boot, Angular, and Kotlin.
- Rewrote backend from JEE to Spring Boot and mobile app from Java to Kotlin (MVVM, Retrofit, Realm).
Key Achievements
- Fixed N+1 performance issues across the system.
- Reduced offline sync time from ~4 hours to 10–15 minutes.
Side Projects
Juntos Family
Rails 8 app I designed and operate: private events, RSVP, wishlists, and Secret Santa. Devise/Argon2, CanCanCan, Solid Queue, i18n (pt-BR/en/es), RSpec with ~95% line coverage.
Ruby on Rails · PostgreSQL · Hotwire · Solid Queue · RSpec
uButeco
Open-source platform to manage restaurant orders, inventory, and kitchen panels, featuring real-time updates, role-based access, and customizable UI.
Ruby on Rails · PostgreSQL · SideKiq · SearchKick · OpenSearch · AnyCable · Argon2 · React · NextJS · TailwindCSS · Redux · Angular · Angular Material · NgRX · JWT · REST APIs
Core Skills
Core Backend
Data & Infrastructure
AI & Integrations
Quality & Delivery
Architecture & Leadership
Also Experienced With
Recommendations
“Lucas is a strong developer, hardworking, and a great collaborator. He consistently goes the extra mile to deliver quality work.”
“Lucas is not only a competent Ruby developer, but also brings positivity and energy to the team. A pleasure to work with.”
“Extremely committed, he always gives his best and has a great desire to learn. He's the kind of person who's truly dedicated; we can always count on him for anything.”
Education
Specialization in Mobile Web Application Development
UniGuairacá Centro Universitário · 2019 – 2021
Bachelor in Internet Systems Technology
Federal University of Technology · 2014 – 2019
Certifications
Microsoft Certified: Azure AI Engineer Associate
Microsoft · 2025
Designs and implements AI solutions on Azure — including Azure OpenAI, Cognitive Services, and ML pipelines — with focus on responsible AI, data grounding, and production-ready integrations.