Leonardo Souza

Implemented secure software development initiatives for the EU and US e-commerce platforms, bringing best coding practices and security reviews to strengthen system integrity and reduce vulnerabilities. Cloud provider: AWS - Amazon Web Services - Design and implementation of financial services features, including tax calculation engine, increasing operational accuracy and reducing financial discrepancies. - Streamlined the financial reconciliation workflow, reducing processing time by 34% through automation of cross-system data validation across payment gateways and invoicing subsystems. - Advocated for security-first development practices for applications in the cloud. - Improved application scalability with event driven approach, using cloud services (AWS SQS). - Implemented a codebase modernization focused on SOLID principles and hexagonal architecture, improving maintainability and modularity. - Collaborated with cross-functional stakeholders in Germany and US (Finance, Product, and DevOps) teams to deliver high-impact features, increasing revenue from B2B customers by improving invoicing accuracy and tax handling. - Assisted in integrating automated testing into GitLab CI/CD pipelines, collaborating with QA and DevOps teams to enhance build validation and release reliability. - Proactively modernized legacy modules, replacing monolithic code with modular, service-oriented architecture using modern standards with cloud resources, improving maintainability and onboarding time for new engineers. - Coached other engineers and conducted code reviews and architecture discussions, fostering a culture of quality and continuous improvement within the engineering department.

Designed and prototyped a cloud-native SaaS centered on image/video engagement. Gained hands-on experience in business model, product design, go-to-market strategy, and technical scalability, despite the project not reaching commercial launch.

(Position ended following the acquisition of the start-up by a larger corporation and the subsequent organizational restructuring: https://de.finance.yahoo.com/nachrichten/massenentlassung-amorelie-steckt-dahinter-151948765.html) Cloud providers: AWS - Amazon Web Services / Adobe Cloud - Extending and modernizing core web application functionalities for an e-commerce platform, with a focus on cloud readiness, performance, and system integration. - Development of web application using Adobe Cloud - Development of web application using Rest APIs - Participating in sprint planning, daily stand-ups, sprint reviews and retrospectives - Contribution to testing and refining solutions - Coached engineers and conducted code reviews and architecture discussions, fostering a culture of quality and continuous improvement within the engineering department.

Architected and modernized backend systems with cloud-native design principles, enabling scalable, resilient, and deployment-ready solutions on Google Cloud Platform. Migrating web applications from traditional architecture and modernizing them using cloud services in GCP and Rest APIs. Cloud provider: GCP - Google Cloud Platform - Advocated and implemented secure, scalable code practices, introducing static analysis tool, code style and unit/integration testing strategies, significantly improving cloud-readiness and deployment safety. - Delivered scalable advertising technology solutions by architecting and deploying cloud-native backend services for a global media platform used in 25+ countries, enabling international business growth and revenue expansion. - Optimized campaign delivery systems, improving performance and reliability under high-load conditions with SQL tuning, reducing downtime and report generation. - Collaborated with DevOps and QA to implement CI/CD pipelines, accelerating release cycles, while maintaining code quality and zero-downtime deployments. - Proactively identified system vulnerabilities and scalability risks. - Coordinated cross-functional engineering efforts across infrastructure, product, and data teams to deliver high-impact features for media clients, contributing to a growth in digital ad revenue. - Applied OKRs to define and track KPIs. - Coached engineers and conducted code reviews and architecture discussions, fostering a culture of quality and continuous improvement within the engineering department.

Developed resilient backend systems and automated recovery mechanisms, enhancing platform stability and minimizing downtime across services used by over 11 million monthly users. - Full-cycle development of core components in the supplier and manufacturer storefront platform of a global e-commerce leader, contributing to a high-availability system supporting 11 - 15 million of monthly active users in the online home retail space. - Optimized codebase across supplier and manufacturer storefront modules, eliminating redundant logic, improving SQL query performance, using caching techniques, and adopting modern design patterns in a in-house built-in framework: Dependency Injection (DI), Repository Pattern and SOLID principles. These efforts resulted in a 35% reduction in server response times, improved backend maintainability, and increased throughput during peak loads - directly enhancing customer experience and enabling smoother product catalog operations for the users. - Advocated for adoption of PSRs (Coding Standard, Coding Style Guide, Logger Interface, Autoloading, Container interface, ...) - Collaborated closely with multidisciplinary teams in US and Germany, to roll out feature updates across multiple country-specific storefronts with zero downtime deployments, accelerating international expansion goals. - Contributed to an agile, innovation-driven culture by actively participating in sprint planning, peer reviews, and technical brainstorming sessions - delivering measurable improvements in delivery timelines and cross-team communication. - Onboarded new team members, fostering a culture of continuous learning and ownership.

Led the development of Brazil’s largest educational national exam platform under strict government security protocols, delivering a mission-critical web system for over 8 million tests. - Led the end-to-end development of a mission-critical web application for Brazil’s ENEM assessment printing and distribution, the country’s largest educational evaluation project and the second-largest in the world, supporting ~8 millions candidates annually. - Operated under national security compliance, without electronic devices, in high-surveillance environments. Cleared to access restricted systems handling sensitive citizen data during the ENEM national examination project (~3 months per year). - Coordinated cross-functional teams and third-party vendors to deliver secure and scalable applications, enhancing collaboration across internal departments and external contractors, ensuring compliance and auditing with national data protection protocols for all candidate records. - Redesigned and restructured legacy systems, improving system reliability and maintainability, reducing critical failure incidents by 32%, and shortening development cycles. - Advocated for the adoption of structured technical specification validation, ensuring architectural consistency and long-term maintainability. - Actively monitored end-to-end system workflows to guarantee performance under national-scale loads. - Led multiple high-stakes web initiatives under tight federal deadlines, delivering features ahead of schedule and contributing to the organization's most profitable and visible projects annually. - Managed approval processes and led implementation phases, aligning technical solutions with business objectives and government contract requirements, resulting in repeat contract renewals and enhanced stakeholder trust.

Redesigned and integrated university systems based in Oracle database to support 12,000+ users, applying early service-oriented principles and data optimization practices. - Designed and developed end-to-end mission-critical web applications with Oracle DB, supporting academic services for over 12,000 students and 250 employees, streamlining academic workflows such as course enrollment, course curriculum grid, grading, and thesis submissions & resulting in an 83% reduction in administrative processing time. - Engineered a service integration layer for seamless data exchange across middleware systems, connecting auxiliary student information systems and databases, enabling real-time synchronization in Oracle-backed databases, reducing data reconciliation errors by over 68% and improving system audit compliance. - Optimized complex Oracle PL/SQL procedures and schema designs, resulting in reduction in average report generation time used by academic employees. - Led knowledge transfer sessions and code walkthroughs for all (junior, middle and senior) developers and IT support employees, reducing support tickets. - Transformed complex institutional needs into scalable technical solutions by collaborating with academic departments and administrative teams, ensuring a 90%+ satisfaction rate in annual user feedback surveys. - Facilitated requirements gathering with non-technical stakeholders, bridging communication gaps and aligning software features with the institution's goals.

Developed and built websites in PHP, ASP, MySQL, Microsoft SQL Server, Javascript, HTML, CSS, Macromedia Flash for small business.

Instructor, giving lectures for private companies and public institutions sectors. Introduction to Informatics Windows Microsoft Office HTML CSS Javascript PHP MySQL