Mobile Software Engineer | Mobile Software Developer

Valter Negreiros

Senior engineer with 10+ years of experience and 10+ published apps. Expert in large-scale mobile transformations, specializing in migrations from Flutter to Native and vice versa, bridging fintech complexity with elite user experiences.

10+
Years Exp.
10+
Apps Published
1M+
Active Users/daily
99%+
Crash-Free
Android & iOSKotlin / SwiftFlutter / DartReact NativeCloud Architecture
Let's ConnectDownload Resume

Experience

Jeitto (5 yrs 1 mo)

Staff Software Engineer @ Jeitto

Oct 2024 – Present

São Paulo, Brazil

Working in multidisciplinary squads, managing the current application architecture and maintaining the quality of the application with tools to assess the health and quality of the code.

  • Led migration from Native Android (Kotlin) to Flutter, architecting custom packages for native sensor and GPS integration.
  • Code review for integration with new releases, managing application updates, writing architecture and implementing quality unit tests.
  • Increasing test coverage and refactoring the current application.
  • Technical lectures on technologies, frameworks and concepts regarding the world of Technology.
  • Architecture development for new product opportunities within the application.

Mobile Specialist @ Jeitto

Jan 2023 – Oct 2024

São Paulo, Brazil

Subject matter expert for mobile platforms, ensuring architectural integrity and implementing robust testing frameworks.

  • Maintenance and development of new features using Android SDK with Kotlin.
  • MVVM, good programming practices, dependency injection, test implementation and state management.
  • Integrations with financial functionalities through REST API using Retrofit.
  • Structured Android test reporting using Kover, JUnit, and Mockito to drive code coverage KPIs.

Senior Mobile Developer | Tech Lead @ Jeitto

Apr 2021 – Jan 2023

São Paulo, Brazil

Led development teams through critical project phases in the fintech space with a focus on high-performance Android implementation.

  • Maintenance and development of new features using Android SDK with Kotlin.
  • Deep expertise in Android SDK, Kotlin, and MVVM architecture.
  • Developed complex financial integrations utilizing Retrofit for secure API communications.
  • Good navigation practices, usability and priority in user experience.

Co-Founder | CTO | Tech Lead @ DViT Solutions

Feb 2018 – Apr 2021

Recife, Brazil

Orchestrated technical strategy and hands-on full-stack development for diverse client projects and product lifecycles.

  • Developed applications for Android (Kotlin), iOS (Swift) and Web (Angular, Vue, React).
  • Architected scalable backends using Java/Spring and Node.js, with MongoDB, MySQL, PostgreSQL, Oracle, Firestore.
  • Implemented custom Android Camera SDK abstraction for KYC workflows.
  • Developed and maintained custom Flutter libraries via Flutter Packages and Channels.
  • Managed full app lifecycle on Google Play Store and Apple App Store.
  • Automated DevOps workflows using Docker and GitLab CI for continuous delivery.
  • Highly recommended internationally for the projects delivered to clients.

Java Web Developer @ Montreal Oficial

Sep 2016 – Mar 2018

Recife, Brazil

Delivered end-to-end software projects for the Pernambuco State Health Department.

  • Implemented MVC architectures using Java (Spring, Hibernate, HQL) for back-end.
  • Front-end with Bootstrap, JSP, AngularJS, jQuery, HTML5, CSS3 and ECMAScript 6.
  • Optimized PostgreSQL databases for high-concurrency healthcare data.
  • Migrated version control from SVN to Git.
  • Automated CI/CD with Jenkins, deploying to Apache on the department's infrastructure.

QA Test Analysis @ Orube Tecnologia

Jul 2015 – Aug 2016

Recife, Brazil

Established rigorous quality assurance standards and automated testing frameworks.

  • Achieved 95% test coverage through Selenium and JUnit automation.
  • Reduced test execution time by 47% via script optimization and parallel Selenium execution.
  • Automated test execution with Gradle integrated into Jenkins CI/CD pipeline.
  • Developed and maintained Selenium WebDriver + JUnit 4 automation framework.

Featured Projects

Termo - Jogo de Palavras

Word game inspired by WORDLE built with Flutter for Android & iOS. Started as an MVP and evolved into one of the most popular apps in Brazil, with 1M+ downloads, 40K+ concurrent daily users and USD 20,000+ revenue in 2 years through Google AdMob and In-App Purchases.

1M+Downloads
4.5+Stars
40K+Daily Users
$20K+Revenue
Download onGoogle Play

World Soccer Quiz 2026

Trivia game for the world's biggest soccer tournament — built with Flutter for Android & iOS. Test your football knowledge with hundreds of questions, covering teams, players, history, and iconic World Cup moments across all editions.

Download onGoogle Play

Nova Advocacia — Law Firm Website

Professional website built for a renowned Brazilian law firm. Designed with a clean, trustworthy aesthetic using pure HTML5, CSS3 and Vanilla JavaScript — no frameworks, maximum performance. Features a responsive layout, smooth scroll animations, service sections and contact form.

Source onGitHub

Sempre IoT

Cross-platform mobile app (Android & iOS) to remotely manage and control IoT devices for home and industrial security & automation. Built with Flutter, utilizing GetX for state management, DIO for HTTP networking, and MQTT protocol for real-time IoT device communication. Powered by a Java Spring backend and Firebase Cloud Messaging (FCM) for push notifications.

Download onGoogle Play
Download on theApp Store

Rastrek

A comprehensive cross-platform ecosystem for 24/7 vehicle tracking and electronic security. Allows users to track vehicles in real-time, view historical routes, set geofences, and receive alerts. Features native mobile apps and a web dashboard.

Download onGoogle Play
Download on theApp Store
Open inBrowser

CPU Clicker

A clicker game where your goal is to generate cycles to turn on your processor. You must upgrade attributes to increase production, push your CPU to the limits, and carefully control overheating to prevent system crashes.

Available onSteam

Berserk Warrior: Infinite Roguelike

An infinite roguelike game built with Unreal Engine 5 using C++ and Blueprints. Features a comprehensive upgrade system, robust save state management, Steam achievements integration, and a dynamic responsive UI. Fully localized across multiple languages using a custom C++ internationalization system.

Available onSteam

Crimson Desert Game Tracker

A lightweight system utility built with C# and .NET to track gameplay sessions for Crimson Desert. It utilizes System.Diagnostics for process lifecycle hooking, System.IO for local session file logging, and System.Threading to efficiently throttle the background monitoring loop without unnecessary CPU consumption.

Source onGitHub

Architecture Showcase

Android Music Player

Multi-Platform Architecture Showcase

KOTLINJETPACK COMPOSEMATERIAL 3CLEAN ARCHITECTURE

A personal study project designed as a full system design & software architecture overview. A single music-player domain implemented across three Android form factors — Phone/Tablet, Wear OS smartwatch, and Android Automotive — each with its own dedicated module, demonstrating platform-specific UX patterns, shared business logic, and clean separation of concerns.

Source code by platform

Phone / TabletWear OSAndroid Auto

Modular Architecture

Feature and platform modules share domain & data layers via Gradle multi-module setup

Clean Architecture

Use-cases, repositories, and ViewModels strictly separated with dependency inversion

Media3 / ExoPlayer

Single MusicPlayerService feeding Phone, Wear OS and Automotive via MediaController

Testability

MockK + JUnit unit tests for ViewModels & Repositories; Kover coverage reports

Architecture Showcase

Weather Challenge

Android Native — MVVM + Hilt + Retrofit

KOTLINJETPACK COMPOSEMVVMHILT + RETROFIT

Android app where the user searches for a city name and instantly sees the current temperature and weather conditions. A clean demonstration of reactive UI patterns, dependency injection and REST API integration in a single-screen app.

Source code by platform

Android (Phone)

MVVM Pattern

ViewModel exposes StateFlow; Compose collects state reactively — no manual lifecycle management

Hilt DI

All dependencies injected via Hilt — Repository, UseCase and ViewModel fully decoupled

Retrofit + REST

Weather API consumed with Retrofit & Gson; errors handled with sealed Result classes

City Search UX

Instant search with debounce, loading states and graceful empty/error states in Compose

Core Expertise

Mobile

FlutterDartAndroid (Kotlin)iOS (Swift)React NativeJetpack ComposeSwiftUIExpoZustand

Web & Frontend

ReactVueAngularTypeScriptJavaScriptHTML5CSS3BootstrapAdminLTE

Backend

JavaSpringKotlinNode.jsExpressMongoose

Game Dev

Unreal EngineC++UnityC#Game DesignGameplay Mechanics

Algorithms & DSA

Data StructuresGraph TheoryDynamic ProgrammingLeetCodeBig-O AnalysisCompetitive Programming

Analytics & Marketing

Google AdMobIn-App PurchasesUXCamMixpanelDataDogA/B TestingFunnel AnalysisUser Retention

Database

MySQLPostgreSQLOracleMongoDBFirestoreRealtime DB

DevOps

JenkinsDockerGradleGitLab CIBitriseMaven

Cloud & Logging

FirebaseNewRelicGoogle CloudPub/SubDatadogGrafana

Testing & QA

JUnitMockitoMockKSeleniumEspressoXCTestKoverTDD

Architecture

MVVMClean ArchitectureMVCRepository PatternSOLIDDI / Hilt / KoinModularization

AI & Innovation

LLM IntegrationAI-assisted devAntigravityClaude CodePrompt Engineering

Soft Skills & Leadership

Tech LeadershipMentoringCode ReviewTechnical LecturesAgile / ScrumCross-functional TeamsInternational ClientsArchitecture Decisions

Public Repositories

music_ai

Music Ai – Android Phone Code Challenge. Full-featured music player with AI integration, ExoPlayer and Wear OS support.

AndroidKotlinWear OSExoPlayer
Kotlin
itunes_challenge_auto

Android Automotive OS challenge app — iTunes music player adapted for in-vehicle infotainment systems.

Android AutoKotlinMedia3
Kotlin
itunes_challenge_wear

Wear OS music player challenge — streaming iTunes tracks on smartwatches with a premium Material UI.

Wear OSKotlinExoPlayer
Kotlin
nova_advocacia_website

Professional law firm website built with HTML/CSS/JS — clean, responsive and client-ready.

HTMLCSSWebsite
HTML
challenge_weather

Android weather app challenge using Kotlin, Retrofit, and MVVM architecture with clean code principles.

AndroidKotlinMVVMRetrofit
Kotlin
android_system_properties

Flutter plugin to access Android system properties natively via platform channels.

FlutterDartPluginAndroid
Dart
pong

Classic Pong game developed with WebSocket using modern web frameworks — Web III course project.

WebSocketJavaScriptGame Dev
JavaScript
openclaude
Fork

Open-source coding-agent CLI for OpenAI, Gemini, DeepSeek, Ollama and 200+ models via OpenAI-compatible APIs.

AICLILLMOpen Source
flutter_inapp_purchase
Fork

Flutter plugin for In-App Purchases — forked and maintained for internal fintech app integrations.

FlutterIAPMonetization
Dart
flutter_barcode_scanner
Fork

Barcode scanner Flutter plugin supporting both Android and iOS — used in production fintech flows.

FlutterBarcodeAndroidiOS
Java
flutter_facebook_app_events
Fork

Flutter plugin for Facebook App Events — used for analytics and marketing attribution in mobile apps.

FlutterAnalyticsFacebook
Dart
open_filex
Fork

Flutter plugin to open files with native apps. Supports iOS (UTI) / Android (intent) / PC (FFI) / Web.

FlutterPluginCross-platform
C++
See all repositories on GitHub

Education & Awards

Systems Analysis and Development

IFPE – Instituto Federal de Pernambuco

Sep 2014 – Jul 2021 · Recife, Brazil

portal.ifpe.edu.br

3rd Place – CONNEPI Award

Exact and Earth Sciences · Banner modality

XI North-East Congress of Research and Innovation · Dec 2016 · Maceió, Alagoas

Scientific Publication – 2016

"Técnicas e Ferramentas de Testes Unitários de Software em Sistemas Armazenados no Portal de Software Público Brasileiro"

Valter Negreiros, Arthur Carvalho, José Roberto de Alencar · IFPE / CONNEPI / IFAL

Language Skills

Levels: A1–A2 Basic · B1–B2 Independent · C1–C2 Proficient

English

C1
Listening
C1
Reading
C1
Spoken
C1
Interaction
C1
Writing

Spanish

B2
Listening
C1
Reading
B2
Spoken
B2
Interaction
B2
Writing

Portuguese

Native
Listening
Native
Reading
Native
Spoken
Native
Interaction
Native
Writing

Beyond the Code

Game Development

Designing systems and experimenting with gameplay mechanics using Unreal Engine (C++) and Unity (C#).

AI-Assisted Development

Experimenting with Antigravity and Claude Code to accelerate prototyping, automate repetitive tasks, and explore new approaches to problem solving.

Driving Licence B

Licensed driver (Category B), based in São Lourenço da Mata, Pernambuco, Brazil.

Let's connect.

Open for technical leadership roles, architectural consulting, or high-impact fintech collaboration.