
Arnaldo Silva Rodrigues Junior
Verified Expert in Engineering
Full-stack AI Developer
Curitiba - State of Paraná, Brazil
Toptal member since April 3, 2015
Arnaldo is a software architect and engineering leader who co-founded and scaled a consultancy to 50+ engineers, serving as CTO and CFO for over a decade. The work he's done across fintech, pharma, telecom, and IoT shaped how he thinks about architecture: systems that evolve, not just ship. Arnaldo's career spans embedded firmware, full-stack development, cloud platforms, and now AI-powered systems with LLM integration.
Portfolio
Experience
- System Integration - 20 years
- Full-stack Development - 18 years
- Solution Architecture - 15 years
- Technical Leadership - 15 years
- Fintech - 10 years
- Fractional CTO - 10 years
- Cloud Architecture - 6 years
- LLM Integration - 4 years
Preferred Environment
React, Node.js, Python, TypeScript, Go, PostgreSQL, AWS IoT, LangGraph, OpenAI API
The most amazing...
...thing I did was start an outsourcing company, scale it to a 50+ engineer organization, and deliver enterprise solutions that companies relied on every day.
Work Experience
Software Architect | Full-stack Developer
Toptal Clients
- Architected AI/LLM integration solutions leveraging Claude and OpenAI APIs with prompt engineering for enterprise applications.
- Implemented 2FA security using FIDO keys and Google Authenticator for cryptocurrency exchange handling sensitive financial transactions.
- Worked on a manufacturing optimization system for pharmaceutical COVID-19 vaccine production using React, Next.js, Python, GraphQL, and D3.js visualization.
- Modernized legacy platforms to React/Next.js cloud-native architectures on AWS and GCP for enterprise telecommunications.
- Developed a WebRTC real-time communications system with FreeSWITCH integration for browser-based VoIP and SIP handling.
- Created an IoT telemetry pipeline with ESP32, OBD-II, and GPS integration for real-time vehicle data streaming and analysis.
- Created Jira-to-Xero integration automating time tracking and invoice synchronization, reducing manual reconciliation overhead.
- Led Angular-to-React migration using micro front-end architecture for an event ticketing platform, modernizing legacy front-end infrastructure.
- Designed a scalable cryptocurrency data platform handling thousands of digital assets with Node.js and a distributed database architecture.
Chief R&D Officer | Partner
Tekna
- Created an R&D division to develop innovative products that are the next step for the company.
- Acted as the CFO of the company from 2018 to 2020. Created a series of KPIs and controls to ensure the financial health and profitability of the company.
- Acted as the lead software architect of the company, team lead, and full-stack developer from 2012 to 2018, working on many projects, mainly using JavaScript with Angular, Node.js, MySQL, PostgreSQL, and Firebase.
- Architected and led a team that built a cash-back system using the concept of double-entry bookkeeping. The web version was built with Angular, and the apps with Ionic. The back end was Node.js on AWS, using Lambda functions and Kubernetes.
- Created new features in Volvo Finance, an iOS application to simulate the monthly payment calculation of the financing of vehicles for the Volvo Group.
- Architected and developed VPSA ERP’s mobile for Android tablets.
- Built billing and charging systems for VoIP providers.
- Started and structured a software-outsourcing business in Brazil from scratch, alongside my business partner, from long-term strategic planning to hiring an office cleaner.
- Built a multi-agent AI trading platform using LangGraph, LangChain, OpenAI, and Claude APIs for market analysis and automated trade execution.
Software Developer Consultant
BRQ
- Allocated as a third-party resource in GBM-HSBC Bank.
- Led the development of the system that communicated with the Brazilian regulatory agency (ANBIMA) about investment funds and managed portfolios and the development of the system that controls the tax payment for those funds.
- Developed the integration to report transactions between the Brazilian and Cayman Island branches to the Brazilian regulatory agency.
Systems Analyst
Global Village Telecom
- Generated network KPI reports using Excel (VBA). Developed a system to monitor the dial-up internet equipment using Perl and SNMP. Generated call center KPI reports.
- Created tools in Excel (VBA) to support CRM and marketing strategy analysis and automated tools to monitor internet dial-up traffic.
- Analyzed data to build BI systems for a VoIP provider and a dial-up internet provider using PL and SQL in an Oracle database.
- Planned CRM processes and marketing strategy analyses based on the information acquired from BI.
- Developed a CRM system using Java and Adobe Flex. Created the Click2Call system. Created a real-time online Flash component compiler.
- Implemented improvements in the billing system of a VoIP provider.
- Led the development of improvements in the service provisioning system and the development of a small service bus.
Intern
Infomatrix Consultoria, Informática e Informação LTDA
- Fixed bugs in a document management system for agro-industries.
- Developed new features for the document management system using VB6.
- Wrote SQL procedures to process information for reports in an Oracle database.
Intern
LAX Eletrônica e Telecomunicações LTDA
- Programmed micro-controllers in assembly language.
- Wrote a library to create a FAT file system over an EEPROM.
- Implemented serial communication using I2C to control peripherals.
- Designed circuit boards and welded electronic boards.
Experience
Multi-agent AI Trading Platform
https://veylor.scienceAutomotive Telemetry and Dashboard Pipeline (ESP32 and OBD-II, GPS, IMU)
WebRTC and FreeSWITCH Browser-based VoIP Tool
Technical Lead for Innovative Fitness Application
Advanced Excel Solutions for Retail Apparel Company
Go Back-end Maintenance for Ticketing Platform
Back-end Services for Proprietary Trading Platform
TypeScript/Next.js Development for Personal Finance Management Portal
Biotech Dashboard
MLM eCommerce Platform
Production System Tier-3 Support and Full-stack Development
Pharmaceutical Manufacturing Insights
Cryptocurrency Exchange Platform
Accessibility Testing API
SMS Message Routing Engine
Textbook Buyback Inventory System
Cryptocurrency Data Platform
Telecom Enterprise Platform Modernization
Educational Technology Platform
IoT Geospatial Mapping Application Architecture
Music Platform Back-end Development
Accounting Workflow Automation with Xero Integration
Healthcare Excel Reporting and Analytics Solution
Financial API Integration Platform for Advertising Agency
Jira-Xero Time Tracking Integration Platform
Airport Mobile Application Development
VPink Sales Management PWA
VoIP Billing and Routing System
Vehicle Financing Simulation Platform
Education
Executive Program in Finance
Wharton Executive Education - Online
Bachelor's Degree in Electrical Engineering - Electronics and Telecommunications
Technological University of Paraná Federal - Curitiba, Brazil
Certifications
Associate Traditional Web Developer
OutSystems Training Team
Skills
Libraries/APIs
Node.js, React, REST APIs, API Development, OpenAPI, SQLAlchemy, Socket.IO, Twilio API, Stripe, RxJS, SOAP APIs, Sockets, Puppeteer, React Redux, WebRTC, Vue, D3.js, Amazon API, Salesforce API, Jira REST API, OpenAI API
Tools
Git, Webpack, Microsoft Excel, Claude, n8n, ChatGPT, FreeSWITCH, Capacitor, MATLAB, Figma, SendGrid, Notion, MQTT, Nx, Claude Agent SDK, Claude Code, Terraform, Jira, Slack, Amazon Cognito, Zapier, BigQuery, Cordova Plugins, Asana, Rollup, Xero, GitHub, Google Kubernetes Engine (GKE)
Languages
SQL, TypeScript, GraphQL, JavaScript, CSS3, CSS, HTML, Python, Excel VBA, Embedded C, UML, Go, Embedded C++, Visual Basic for Applications (VBA), Java, C++, x64 Assembly, Assembly, C#, Kotlin, Swift, VHDL, PHP, Sass
Frameworks
Angular, Ionic, Express.js, React Native, Tailwind CSS, Agentic Frameworks, JSON Web Tokens (JWT), Swagger, Next.js, Django, Redux, Flutter, Flask, NestJS, OAuth 2, Sails.js, LangGraph, Spring Boot, AngularJS
Paradigms
MEAN Stack, Microservices, Agile, Object-oriented Programming (OOP), Behavior-driven Development (BDD), Agile Software Development, Test-driven Development (TDD), ETL, B2B, Mobile Development, Database Development, Cross-platform, Testing, Back-end Architecture, DevOps, Web Performance Optimization (WPO), Automation, Real-time Systems, Model Context Protocol (MCP), UI Design, Responsive Web Design (RWD), HIPAA Compliance, Unit Testing, REST, Agile Workflow
Platforms
Amazon Web Services (AWS), iOS, Firebase, Mobile, Docker, Kubernetes, Android, AWS Lambda, Amazon EC2, Twilio, STM32, Google Cloud Platform (GCP), Apache Kafka, Azure, Blockchain, Vercel, AWS IoT, Salesforce, Google Cloud Engine
Storage
JSON, PostgreSQL, NoSQL, MongoDB, MySQL, Redis Cache, Data Pipelines, Amazon Aurora, Google Cloud, Neo4j, Amazon S3 (AWS S3), Amazon DynamoDB, Elasticsearch, Google Cloud Datastore, Google Cloud Spanner, PostGIS
Industry Expertise
Project Management, Healthcare
Other
CTO, APIs, Cloud Architecture, Full-stack, API Integration, Software Architecture, Architecture, Solution Architecture, Software Development Lifecycle (SDLC), Fintech, Artificial Intelligence (AI), Mobile Applications, Technical Leadership, Full-stack Development, User Experience (UX), User Interface (UI), Leadership, Fractional CTO, Minimum Viable Product (MVP), Concurrency, Scalable Web Services, Excel 365, Team Management, Technical Architecture, Back-end Development, Deployment, Software Design, Integration, Mobile App Development, Front-end, Prompt Engineering, OpenAI, Agentic AI, AI/ML Data Engineering, Autonomous AI, Large Language Model (LLM) Optimization, AI Solutions Architecture, Microcontrollers, Webhooks, TCP/IP, Session Initiation Protocol (SIP), System Integration, SMTP, Product Delivery, Software System Architecture Development, AI Agents, AI Programming, System Design, AI Architecture, Firebase Cloud Functions, Backups, Scalability, Product Discovery, SaaS, AI Architect & Full-stack, LLM Integration, Distributed Systems, SDKs, Code Review, OutSystems, Authentication, AWS Cloud Architecture, Mobile Apps, Performance, Data Engineering, Serial Communication, CI/CD Pipelines, Accessibility, Large Language Models (LLMs), Cordova, IP Telephony, Telephony, PBX, Web Scraping, FPGA, Embedded Systems, Supabase, FastAPI, Bootstrap 4, ERD, Electrical Engineering, Firmware, Hardware, Reverse Engineering, Cloud Infrastructure, Anthropic, LangChain, SMS, Customer Relationship Management (CRM), Firmware Development, GPS, On-board Diagnostics II (OBD-II), ESP32, Real-time Operating System (RTOS), Logic Analyzers, FreeRTOS, CAN Bus, Printed Circuit Board (PCB), Bluetooth Low Energy (BLE), RTP, Firmware over the Air (FOTA), WCAG 2, Web Content Accessibility Guidelines (WCAG), AWS Database Management System, Board Reporting, Generative Artificial Intelligence (GenAI), Vite, Retrieval-augmented Generation (RAG), Communication, Security, Startups, Cursor AI, AI Integration, WebSockets, MCP server, TypeORM, Robotics, Web Development, Progressive Web Applications (PWAs), Digital Transformation, Digital Payments, Marketplace Lending, Consumer Banking, Insurance Technology (Insurtech), Technology, Cryptocurrency, Regulations, Real Estate, Cloudflare, Google BigQuery, Data Science, Machine Learning, Universal Asynchronous Receiver/Transmitter (UART), Automated Trading Software, Trading Bots, Trading, Google Agent Development Kit, Excel Dashboards, GitOps, ParcelJS, Back-end, High Code Quality, Reporting, Detail-oriented, VoIP, Finance, FastMCP, Internet of Things (IoT), Telemetry
How to Work with Toptal
Toptal matches you directly with global industry experts from our network in hours—not weeks or months.
Share your needs
Choose your talent
Start your risk-free talent trial
Top talent is in high demand.
Start hiring