Senior Go Engineer (Colibrix Partners)

Colibrix Limited; Warszawa; Hybrid; PLN 180,000 - 280,000; Full time

Benefits offered by this job

Competitive salary

Flexible work arrangements

Learning opportunities

Job summary

COLIBRIX ONE is seeking a Go backend developer to build and scale the card-issuing platform, wallets, and related services. You will translate business requirements into robust technical specifications, contribute to microservices architecture, and ensure secure, scalable data handling across PCI DSS-compliant components.

The role emphasizes performance optimization, collaboration within a fintech-focused team, and building high-availability systems using modern observability tools.

Qualifications

• 3–5 years of Go backend development in fintech environments.
• Experience with distributed systems and API design (REST/RPC).
• Familiarity with SQL/NoSQL databases, message brokers (Kafka, NATS), caching.

Responsibilities

• Design and develop Go-based services for the card-issuing platform and wallets.
• Translate business requirements into technical specs and API designs.
• Ensure security requirements (PCI DSS) and secure inter-service communication.
• Analyze performance and optimize storage/network use.
• Contribute to microservices architecture and service boundaries.
• Write maintainable unit/integration tests and participate in code reviews.

Skills

Go backend development

Fintech experience

Distributed systems

API design

English & Russian

Tools

Kafka

NATS

GitLab

AWS

Prometheus

Grafana

Kubernetes

REST/gRPC

SQL

NoSQL

Job description

At COLIBRIX ONE*, we're building advanced, AI-powered payment technologies that support Payment Service Providers (PSPs), Electronic Money Institutions (EMIs), and neobanks across the EU and the UK. As a fully licensed Electronic Money Institution (FCA Reference No. 927920) and holder of a Financial Institution Licence issued by the MFSA, as well as a principal member of both VISA and Mastercard, we provide comprehensive, real-world financial solutions that include:

• Global card processing
• Digital wallet infrastructure
• Cross-border merchant accounts
• Alternative payment methods (APMs)
• Corporate accounts for legal entities

We're a fast-growing team with a passion for innovation, security, and scalability. Our culture values curiosity, collaboration, and impact - and we're looking for talented professionals who are ready to shape the future of fintech.

At COLIBRIX ONE, your work directly powers the digital economy. If you're eager to solve meaningful challenges and build with purpose, we'd love to hear from you.

Tech stack:

Go, MongoDB, Redis, NATS, JetStream, REST/gRPC, AWS, Kubernetes, GitLab CI/CD, ArgoCD, Prometheus, Grafana.

Key responsibilities:

• Design and develop Go-based services for the Colibrix Partners card-issuing platform — card lifecycle (issuance, top-ups, blocks, replacement, expiry), wallets and balances, fees and commissions, authorisation and clearing flows — with a focus on stability, fault tolerance, and correct handling of financial operations
• Translate business requirements into clear technical specifications and propose concrete solutions at the service and module level, including API design, data models, and integrations with external providers
• Build solutions in compliance with security requirements, including PCI DSS, proper handling of sensitive data, and secure inter-service communication
• Analyze and optimize service performance, including code profiling, concurrency handling, and efficiency of data storage and network interactions
• Participate in the architecture of microservices: service boundaries, communication patterns, load balancing, error handling, queues/streaming, and data storage approaches
• Produce maintainable, testable code with appropriate unit and integration test coverage, following team development standards
• Participate in code review as part of the development process: evaluate implementations, identify issues, and provide constructive feedback aligned with technical requirements
• Contribute to technical discussions by offering concrete, practical solutions within the current architecture and development processes
  

What You Need to Succeed in This Role:

• 3–5 years of Go development experience focused on backend systems, and around 3 years of experience working with fintech applications
• Understanding of distributed systems, microservices architecture, and API design, including REST/RPC transports
• Experience working with SQL and NoSQL databases, message brokers (Kafka, NATS), and caching systems
• Familiarity with CI/CD practices and tools, preferably GitLab
• Experience working with the AWS cloud platform
• Ability to contribute expertise and collaborate with the team on technical solutions
• Strong communication skills and the ability to explain complex technical ideas to colleagues with varying levels of technical background
• Fluency in written and spoken English and Russian
• Experience in the fintech domain
• Security-by-design mindset: ability to design solutions with security considerations built in at every stage
• Understanding of regulatory requirements in the fintech space (e.g., PCI DSS, GDPR)
• Experience in performance optimization and building high-availability systems
• Experience with observability tools: logging, metrics, tracing (Prometheus, Grafana, OpenTelemetry)
  

What We Offer:

• Opportunity to shape the future of fintech solutions within a growing company
• Collaborative, horizontal team structure that values your expertise and ideas
• Continuous learning and development opportunities to enhance your skills and career growth
• Competitive salary and benefits package
• Flexible work arrangements to support work-life balance

* This position is offered within the COLIBRIXONE. Employment will be under the appropriate legal entity based on the role and location.