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:

General 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 COLIBRIX ONE. Employment will be under the appropriate legal entity based on the role and location

📌 Senior Go Engineer (Colibrix Partners) (Madrid)
🏢 Colibrix One
📍 Madrid