Backend systems · Financial platforms · Distributed architectures

Gabriel Reis

Senior Software Engineer focused on backend systems, financial platforms, and distributed architectures.

I design and build reliable Java-based systems for regulated, high-scale environments - combining clean architecture, event-driven design, performance engineering, and production reliability.

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Professional portrait of Gabriel Reis

Current focus

JavaSpring BootAWSKafkaKubernetesDDDFinancial SystemsTrading SystemsEvent-Driven Architecture

Selected impact

Concrete outcomes from production backend work.

A concise view of systems work across financial services, public-sector platforms, performance improvements, and distributed service ecosystems.

5+

Years of software engineering experience

5

Financial microservices delivered for PIX compliance

60%

Messaging cost reduction through SNS/SQS consolidation

92.5%

Endpoint performance improvement, from 8s to 600ms

40+

Features delivered for a No-Code ERP/Web framework

14+

Services supported in distributed onboarding ecosystems

Experience

Career timeline across financial, enterprise, and public-sector systems.

Backend delivery with architectural ownership, production constraints, and cross-functional collaboration.

  1. Current engagement

    Foursys / BTG Pactual

    Senior Software Engineer

    • Currently working through Foursys on BTG Pactual's trading platform, specifically the Balance Online system.
    • Contributing to backend services that support mission-critical financial operations where accuracy, resilience, and traceability are essential.
    • Working in a trading context with strong attention to production reliability, performance, maintainability, and operational risk.

  2. January 2025 - Present

    NTT DATA Europe & Latam

    Senior Software Engineer

    • Led the architectural refactoring of Bradesco's BFF layer into a modular monolith using Hexagonal Architecture and DDD.
    • Established bounded contexts and helped isolate business rules from API gateway responsibilities.
    • Authored an ADR to formalize architectural decisions and guide team adoption.
    • Reduced production bugs and merge conflicts by decomposing god classes into well-defined business contexts.
    • Delivered 5 financial microservices supporting PIX compliance for Banco PAN using reactive Spring Boot and Bacen-compliant practices.
    • Co-developed a native Java workflow engine for Bradesco, enabling BPMN-like programmatic workflow definition.
    • Consolidated 3 isolated SQS queues into a unified SNS + SQS architecture, reducing operational messaging costs by 60%.

  3. June 2024 - January 2025

    LightHouse

    Mid-level Developer

    • Engineered and optimized microservices for Cresol's account onboarding ecosystem with 14+ services.
    • Used Java, Spring Boot, RabbitMQ, and Camunda across critical backend flows.
    • Modernized a mission-critical onboarding flow using BPMN and Camunda.
    • Improved a key endpoint by 92.5%, reducing response time from 8s to 600ms.
    • Worked closely with architecture, product, QA, and business teams.

  4. July 2023 - June 2024

    Topos Informatica

    Mid-level Developer

    • Designed and built a modern legal reporting system for FAPESB using Java 17, Spring Boot, and Tomcat 10.
    • Replaced a legacy solution with a robust backend platform.
    • Improved traceability, compliance, and performance for public-sector processes.
    • Added observability using Prometheus and Grafana.
    • Migrated legacy monolith features to REST-based microservices.
    • Improved system efficiency by 25% and reduced response time by 15%.

  5. March 2022 - July 2023

    Softwell Solutions

    Software Engineer

    • Improved the Maker No-Code framework for ERP and web application development.
    • Delivered 40+ features across framework, backend, and dynamic UI capabilities.
    • Used Java Reflection and multithreading to improve dynamic behavior execution.
    • Built dynamic HTML grid generation from datasets.
    • Built a smart Excel upload tool that auto-generated HTML forms and database tables.

Case studies

Consulting-style notes on selected backend work.

Short case notes focused on the problem, the technical approach, and the operational impact.

Case 01

PIX Compliance Microservices

Financial-grade backend systems for regulated environments

Problem
Banco PAN needed backend services aligned with PIX and Bacen requirements, where traceability, correctness, and regulatory fit were central constraints.
Approach
Gabriel helped deliver five financial microservices using reactive Spring Boot practices, with attention to service boundaries, integration behavior, and production reliability.
Impact
The work supported PIX compliance initiatives in a regulated banking environment.

Technologies: Java · Spring Boot · Reactive Systems · PIX · Bacen · Microservices

Case 02

Modular Monolith Refactoring for Bradesco

From BFF complexity to clear business boundaries

Problem
The BFF layer had accumulated broad responsibilities, making business rules harder to isolate and increasing the cost of change.
Approach
Gabriel led a refactoring toward a modular monolith using DDD and Hexagonal Architecture, establishing bounded contexts and documenting the direction through an ADR.
Impact
The refactor improved maintainability, reduced merge conflicts, and made ownership of business behavior easier to reason about.

Technologies: DDD · Hexagonal Architecture · Modular Monolith · ADR · Clean Architecture

Case 03

Event-Driven Messaging Cost Optimization

Consolidating SQS queues with SNS/SQS architecture

Problem
Three isolated SQS queues created unnecessary operational cost and fragmentation in an event-driven flow.
Approach
Gabriel consolidated the messaging flow into a unified service using AWS SNS and SQS, keeping the design aligned with asynchronous processing needs.
Impact
The change reduced operational messaging costs by 60%.

Technologies: AWS · SNS · SQS · Event-Driven Architecture · Messaging · Cloud

Technical expertise

Technologies and practices used in production systems.

A practical backend toolkit for Java services, distributed architectures, cloud platforms, observability, and performance work.

Backend

Java 8-21Spring BootQuarkusREST APIsMicroservicesServletsJSP

Architecture

Distributed SystemsEvent-Driven ArchitectureDDDHexagonal ArchitectureClean ArchitectureCQRSModular MonolithsSystem Design

Messaging

KafkaRabbitMQAWS SNSAWS SQS

Cloud & DevOps

AWSAzureGoogle CloudDockerKubernetesCI/CDVercel for this site

Observability

PrometheusGrafanaDistributed TracingPerformance Tuning

Databases

PostgreSQLRelational DatabasesDatabase modelingQuery optimization

Practices

TDDADRsClean CodePerformance OptimizationProduction Reliability

Engineering insights

Notes Gabriel is preparing from production backend work.

A quiet writing area for practical essays on financial systems, architecture decisions, and operational reliability.

Coming soon

Designing Idempotent Payment Systems

A practical note on retries, deduplication, traceability, and failure modes in financial backend flows.

Coming soon

Modular Monoliths in Financial Platforms

How bounded contexts and explicit module ownership can reduce coordination cost without forcing premature microservices.

Coming soon

Event-Driven Architecture with Operational Responsibility

Why message brokers are only one part of the design, and how observability, retries, and ownership shape production behavior.

Contact

Let's build reliable systems.

Available for senior backend engineering roles and conversations around financial systems, architecture modernization, and production-grade Java platforms.

Email GabrielLinkedIn
Email
gabriel.mcd.reis@gmail.com
LinkedIn
linkedin.com/in/gabriel-reis-java
Location
Brazil