AI-Native Fullstack Engineer (Go + React)

Job Description

Join COLIBRIX ONE - Innovating the Future of Payments

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 EMI (FCA reference number 927920) and a Principal Member of Mastercard, we offer 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.

About the Role
We write detailed technical specs. Your job is to turn them into working product by orchestrating AI coding agents — and to own the quality of everything that ships. Our toolchain is Claude Code with custom skills on top of a structured spec pipeline; if you bring approaches that have worked for you, we are happy to compare and adopt what proves effective. You will work directly with the coordinators of this direction: the agentic development process is already up and running, and you will be its first dedicated engineer.

Responsibilities

• Take a spec and drive it to production: clarify ambiguities with the spec author instead of guessing, decompose work into small verifiable increments, execute via AI agents
• Design verification before generation: acceptance criteria, tests, invariants and API contracts that make agent output checkable
• Review and accept agent-generated code: catch silent scope creep, tests fitted to bugs, hallucinated APIs, code that passes but does the wrong thing
• Step in and code by hand when an agent hits a dead end (mostly Go)
• Build and tune the agent toolchain: skills, prompts, guardrails, workflows — and measure what matters: first-pass acceptance rate, rework volume, spec-to-production cycle time

• What You Need to Succeed in This Role
  3–5 years of professional software engineering experience
• Strong Go backend engineering: services, APIs, concurrency, data consistency — this is where mistakes cost the most (our stack: MongoDB, NATS, gRPC)
• Comfort with event-driven architecture: any message broker (we use NATS), idempotent consumers, outbox, sagas/compensations, retries with DLQ, eventual consistency
• Working React/TypeScript: enough to deliver and review SPA features built on top of our APIs
• Payments/fintech experience is a strong plus: idempotency, transactional integrity, money handling, audit trails; subscriptions and recurring billing — an even stronger plus
• Proven ability to read, debug and refactor code you didn't write — most of this role is review and acceptance, not typing
• Hands-on production experience with AI coding agents — not demos
• Discipline to work from specs and keep requirement → code → test traceability
  

Growth path: today you own delivery on a dedicated project; as the agentic approach scales across the company, you help engineers from our classic development track adopt it.

Who this is NOT for: engineers who want to hand-write most of their code, or who accept generated code they haven't tried to break.

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 

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