lucianosantos.dev

About

Mobile software engineer.

I’m a software engineer with 12+ years of experience across fintech and medtech, with a strong focus on native Android.

Most of my career has been in the payment industry — Android SmartPOS apps, embedded Linux POS terminals, and Tap-to-Pay SDKs — where compliance with PCI and EMV is non-negotiable. Right now I’m consulting on Android payment SDKs for SmartPOS terminals: EMV flows, certification readiness, modern architecture, automated testing, and CI/CD. I’ve also delivered HMIs for medical devices aligned with IEC 62304, software that has been deployed in clinical trials.

I care about clean, maintainable code, strong CI pipelines, and getting cross-platform delivery right. My core stack is Kotlin, Jetpack Compose, and KMP, with Qt/C++20 and QML for embedded and desktop targets, plus Python and Bash for automation.

Based in Rio de Janeiro, Brazil. Open to remote roles with high-impact teams in Android or embedded engineering.

Experience

  1. Independent Software Consultant — Fintech & Payment Systems · Confidential clientsNov 2025 – Present · Remote
    • Architecting Android payment SDKs and reference apps for SmartPOS terminals, covering contact, NFC, and magstripe EMV flows for fintech clients in Europe and Brazil.
    • Designing modular, hardware-agnostic architectures with TDD and hexagonal patterns so the same SDK integrates with different gateways and terminals.
    • Writing the technical integration documentation and developer guides that third-party teams use to adopt the payment features.
    • Modernizing legacy ecosystems with Jetpack Compose and MVI, driving products through final stability phases and EMV certification readiness.
  2. Senior Software Developer · VitalTraceApr 2024 – Oct 2025 · Perth, Australia · Remote
    • Delivered responsive HMIs for medical devices in C++/Qt, aligned with IEC 62304 and deployed in clinical trials.
    • Designed cross-platform UIs (Windows / Linux / Embedded) for clinician-facing touchscreen tablets.
    • Integrated BLE communication to capture and display real-time device data in the HMI.
    • Automated builds, static analysis, testing, and deployment on GitHub Actions with custom Bash and Python scripts.
    • Built a Streamlit dashboard for the data science team to persist and analyze sensor data.
  3. Senior Software Developer · ZoopApr 2023 – Apr 2024 · Rio de Janeiro, Brazil · Remote
    • Developed a Tap-to-Pay SDK for Android, adopted by major fintech clients including Nubank.
    • Automated white-label app delivery for 30+ clients on Google Play with Fastlane + GitHub Actions, cutting release effort from a week to under an hour.
    • Monitored post-release crash rates with Firebase Crashlytics, contributing to a significant drop in production incidents.
    • Implemented CI pipelines with unit/UI testing, static analysis, and coverage reporting.
    • Built Android apps for Bluetooth and USB-serial payment terminals; used KMP to share business logic across smartphone, SmartPOS, and desktop.
    • Supported EMV-certified flows aligned with PCI DSS.
  4. Senior Software Developer · CloudWalkAug 2022 – Oct 2022 · São Paulo, Brazil · Remote
    • Introduced an interface-based architecture to an existing Android SmartPOS app so it could support multiple devices.
    • Implemented the Ingenico DX8000 backend while preserving Verifone support, keeping feature parity and consistent performance.
    • Introduced unit testing and TDD practices to the team.
    • Implemented GitHub Actions CI pipelines with automated test runs and coverage reporting.
  5. Senior Software Developer & Partner · AditumFeb 2019 – Mar 2022 · Rio de Janeiro, Brazil
    • Built white-label POS applications for Linux-based S920 and Android-based A910 terminals, customized per client.
    • Developed an Android SDK for mPOS device integration over Bluetooth and serial USB, with sample apps and documentation.
    • Created desktop applications integrating POS systems with Verifone V200 and Gertec PPC920/PPC930 pinpads.
    • Ran MasterCard and Visa brand certifications hands-on with BTT UL tools, covering contact and contactless EMV.
    • Collaborated with backend teams on ISO 8583 integrations.
  6. Software Developer · StoneNov 2016 – Feb 2019 · Rio de Janeiro, Brazil
    • Contributed from day one to a new embedded-Linux POS project that grew past 100k terminals and now serves millions.
    • Built Qt apps for POS devices (S920, Q90, D195) and frontend components for on-device web apps.
    • Introduced a hardware abstraction layer to migrate the main POS system from PAX S920 to Verifone V240.
  7. Software Development Intern · Radix Engenharia e SoftwareNov 2015 – Jul 2016
    • Worked on a fleet management web app for Sotreq CAT.
  8. Frontend Developer · CERNMay 2013 – Aug 2013 · Geneva, Switzerland
    • Automated tracking and management of scientific publication authorship across the global LHCb collaboration.
    • Built a web app for HR management of LHCb collaboration members.

Education

Federal University of Rio de Janeiro (UFRJ) — B.Sc. Electronic & Computing Engineering · 2010 – 2018

  • Thesis: robot project for automated testing of credit card machines.
  • Electronics & Programming Division Coordinator, MinervaBots robotics competition team.

Skills

Native Android
Kotlin, Jetpack Compose, Java, MVVM, MVI, Coroutines, Koin, Room, Firebase
Cross-platform
Kotlin Multiplatform, Qt / C++20
Embedded
C++20, Qt, QML, Buildroot, Linux
Architecture
Clean Architecture, Hexagonal, TDD, OOP
CI/CD
GitHub Actions, Azure DevOps, Fastlane
Scripting
Python, Bash
APIs
REST + GraphQL via Ktor, okhttp, Retrofit, QtNetwork
Testing
JUnit, Mockk, Mockito, Espresso, Firebase Test Lab, Google Test, QTest
Payments
EMV, PCI DSS, ISO 8583, Tap to Pay, SmartPOS
Methodology
Agile / Scrum

Languages

  • Portuguese — Native
  • English — Full professional proficiency (B2)
  • French — Basic

Get in touch