Andrezza Medeiros

Software Engineer with 4+ years building backend systems and APIs in production. Strong in Java and Spring (Boot, Security, Data), with Go and C#.

Experience across security, messaging infrastructure (Kafka, NATS), and multi-tenant systems in regulated finance and enterprise domains. Works in Agile, English-speaking international teams. Based in Germany, B1 German.

Software Engineer at Zertificon Solutions GmbH (2024-05 – Present)

Secure messaging platform for enterprise clients including Lufthansa and VKB.

• Built a custom TLS/SSL authentication layer across 10+ microservices serving ~200 enterprise tenants, replacing insecure certificate handling.
• Integrated NATS JetStream for encrypted mail delivery, processing 50K–5M messages/day (10GB+) with guaranteed delivery and fault tolerance.
• Fixed a production deadlock causing ~2 hours/day of downtime by redesigning a synchronous flow into an async queue.
• Fixed 4 high-severity vulnerabilities: Cross-Site Scripting (XSS), OTP replay, sensitive data exposure, and an antivirus bypass.
• Built an end-to-end notification system for a major European airline client: template engine, media handling, and automated cleanup.
• Tuned container orchestration: deployment configs, resource limits, and health checks.

Freelance Software Developer at Freelance (2023-09 – 2023-12)

• Built a full-stack authentication and authorization system for an e-commerce client.
• Implemented JSON Web Token (JWT) and OAuth 2.0 with role-based access control (RBAC).

Software Engineer at Zup Innovation (2021-10 – 2023-03)

APIs for Itaú Bank across Stock Market and Internet Banking segments.

• Built and maintained APIs handling millions of transactions and users.
• Built Kafka event-processing pipelines handling ~3M daily transactions on the Brazilian stock exchange.
• Modernized system architecture with client teams, cutting deployment time ~30%.

Backend Developer at Kyros Tecnologia (2020-06 – 2021-10)

• Built backend APIs for financial reconciliation systems in Card Services and Telephony segments.
• Automated spreadsheet workflows with VBA and SQL Server reporting, saving ~6 hours/week across a team of 8.

Programming Teacher at Byju's Future School (2022-09 – 2024-04)

• Taught programming, algorithms, and software fundamentals (JavaScript, React, game development) to students aged 11–14.

B.Sc. in Computer Science – UNITRI (2020-02 – 2024-06)