Gabriel Trzimajewski

Senior Backend Software Engineer

Gabriel Trzimajewski — Senior Backend Software Engineer, Blumenau, Santa Catarina, BR.

Summary

Backend-focused Software Engineer with 5+ years building distributed systems, APIs, and cloud infrastructure at scale. Currently at Paytrack, working with Java and Spring Boot on the backend and React with TypeScript on the frontend. Previously at K2 Partnering Solutions, allocated to Bradesco on an internal observability and log-processing platform operating at banking scale, with audited incident-based access workflows and legacy Java 8 modernization. Before that at Mundo Invest, where he led a B3 stock exchange integration API handling ~100k requests/day for ~10k monthly active users, cut AWS costs by ~50% through a Terraform region migration and rightsizing, reduced incident investigation time by ~80% with Datadog SLO alerting, and took PostgreSQL search queries from ~8s to under 200ms. Comfortable across Java and Spring Boot, TypeScript and Node.js, and Go. Strong on reliability engineering, observability, messaging with Kafka and gRPC, cost optimization, database performance tuning, financial and banking-scale systems, legacy modernization, and mainframe-to-web integration. Also working in applied AI at the application and infrastructure layer with LangChain, the AI SDK, and Claude Code including Skills and MCP servers. Self-taught, systems-oriented, focused on reliability and performance.

Skills

Java
Spring Boot
Node.js
React
TypeScript
Observability
AWS
B3
Incident Investigation
gRPC
PostgreSQL
Kafka
Datadog
Java 8
Go

Experience

Senior Software Engineer, Paytrack

Gabriel Trzimajewski works as Senior Software Engineer at Paytrack, since September 2026.

Backend engineer working with Java and Spring Boot, contributing to the frontend with React and TypeScript.

Senior Software Engineer, Bradesco

Gabriel Trzimajewski worked as Senior Software Engineer at Bradesco from April 2025 to July 2026.

Allocated to Bradesco via K2 Partnering Solutions as a backend engineer on the Open Platform team, working on an existing internal log processing and observability platform used at banking scale for incident investigation and system monitoring, where he shipped new features and led the modernization of its legacy components.

Shipped new features into the existing log processing and observability platform used by Bradesco analysts to investigate incidents and monitor systems.
Designed and implemented an audited, incident-based log access workflow in which analysts retrieve logs by providing a ticket ID, eliminating manual access approvals from managers.
Reduced investigation time by more than 50% by removing the manual approval step from the log access path while keeping every query automatically audited.
Ensured full traceability and regulatory compliance by automatically auditing every log query against its originating incident ticket.
Led the modernization of a legacy Java 8 system through architectural refactoring, improving scalability and long-term maintainability.
Removed accumulated technical debt from the legacy codebase, reducing maintenance cost and making the system safer to change.
Redesigned the storage strategy for log data, optimizing resource usage and lowering infrastructure costs.
Implemented integrations between mainframe systems and modern web services in Java, bridging legacy infrastructure with distributed services.
Worked with Java and Spring Boot across the platform's ingestion, query, and access-control paths.
Operated inside a regulated banking environment where audit, compliance, and traceability requirements shaped the architecture.

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Backend Software Engineer, Mundo Invest

Gabriel Trzimajewski worked as Backend Software Engineer at Mundo Invest from February 2024 to March 2025.

Distributed microservices for a Brazilian investment platform, including a B3 stock exchange integration API, AWS infrastructure, and observability.

Led development of a B3 (Brazilian stock exchange) integration API handling ~100k requests/day for ~10k monthly active users, enabling real-time stock transaction tracking.
Designed the B3 integration as a client-facing aggregation layer over internal services, a Backend for Frontend (BFF) exposing REST endpoints, webhooks, and Kafka consumers.
Built and maintained microservices with NestJS and TypeScript in a multi-repo microservice environment.
Designed and documented REST APIs extensively with OpenAPI/Swagger, giving client teams a contract they could build against without back-and-forth.
Improved test coverage and observability with JUnit and Datadog, reducing incident investigation time by ~80% and lowering MTTR across a 5-engineer team.
Migrated AWS infrastructure across regions using Terraform, reducing cloud costs by ~50% through workload analysis and rightsizing.
Designed Datadog dashboards and SLO-based alerting, improving error budget tracking and production reliability.
Automated CI/CD pipelines with GitHub Actions, Docker, ECS, and ECR, reducing deployment time from 15 minutes to 3 minutes.
Replaced synchronous REST communication with gRPC on latency-sensitive paths, reducing inter-service latency and improving tail performance.
Optimized PostgreSQL search queries using pg_trgm, reducing response times from ~8s to under 200ms under production load.
Developed and maintained distributed microservices and AWS Lambdas in Java with Spring Boot, Node.js with TypeScript and Express, and Go.
Engaged in architectural and communication design discussions with teams working on Kafka and gRPC integrations.
Led refactorings that improved cohesion and reduced coupling across services, alongside code performance improvements.
Worked with PostgreSQL and MongoDB as primary data stores across services.

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Full Stack Engineer, Mercante

Gabriel Trzimajewski worked as Full Stack Engineer at Mercante from July 2021 to February 2024.

Part-time contract engineering for Mercante, a Paraguay-based digital agency. E-commerce platforms and self-hosted infrastructure for SMBs in Brazil and Paraguay, several of which are still in production today.

Designed and delivered e-commerce platforms for 10+ small and medium businesses across Brazil and Paraguay through Mercante, achieving an average 30% increase in client sales after launch.
Shipped storefronts that are still live and serving customers in production years after delivery.
Architected self-hosted VPS infrastructures, cutting operational costs versus SaaS alternatives while retaining full control over performance and deployments.
Built storefronts with React, TypeScript, and Node.js, focusing on performance, SEO, and conversion.
Delivered backend services using NestJS.
Managed the full project lifecycle end to end: discovery, design, development, deployment, and post-launch support.
Worked directly with non-technical business owners to turn commercial goals into technical scope.

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Education

B.Sc. (in progress, expected Feb 2029), Computer Science

Gabriel Trzimajewski is studying Computer Science at UNINTER (2025-02 – 2029-02), with a GPA of 9.18/10.

Algorithms, Data Structures, Databases, Distributed Systems, Calculus, Linear Algebra, Probability and Statistics, Artificial Intelligence, Cloud Computing

Languages

Portuguese, Native speaker
English, Fluent (C1)