Senior Backend Developer

Yuno · Spain · posted 689mo ago

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About this role

Remote · Full Time · Individual Contributor · +5 Years of Experience

Senior Backend Developer

Who We Are

Yuno is the AI-native operating system of global commerce, powering the financial infrastructure of enterprise merchants, banks, and wallets. Through a single API, Yuno connects them to pay-ins, payouts, fraud prevention, KYC/KYB, and stablecoins globally, so they can operate everywhere. Agnostic by design and connected to 1,000+ payment methods and 460+ integrations in 190+ countries, Yuno optimizes acceptance rates, reduces costs, and strengthens security through specialized AI agents that learn from every transaction. Global brands including McDonald's, NetEase Games, GoFundMe, and Rappi run their payments on Yuno.

About The Role

Yuno is looking for a Backend Developer to join the Checkout Team — one of our most critical squads, responsible for the core transaction processing engine behind our checkout flows at scale. You'll design and build the systems that handle millions of payment transactions globally, alongside a world-class engineering team in a fast-paced, high-impact environment.

Our core backend stack is Kotlin and Go — experience with either is a strong plus, though we care most about solid engineering fundamentals and depth in payments.

How AI Shows Up in This Role

The checkout engine you build is where Yuno's smart routing and fraud-prevention agents act — your services carry the transactions those AI agents learn from and optimize on every payment
AI is our default execution layer: you're encouraged to use AI-assisted tooling across design, implementation, testing, and reviews, and to bring it to our technical exercises. We care how you use it, not whether you do

Your Contribution Will Be

High-performance backend services — design, build, and evolve backend services and APIs in Kotlin and Go, engineered for reliability, low latency, and massive scale
Checkout payment flows — develop and maintain authorization, capture, refunds, reversals, and partial payments across multiple providers and regions
Event-driven microservices — architect resilient microservices using event-driven patterns (Kafka, queues) to handle asynchronous payment processing with zero data loss
Integration framework — strengthen and expand the framework that connects Yuno to PSPs, acquirers, and payment gateways across countries and complex payment rails
Security and compliance — apply OWASP principles and engineering best practices to ensure security, privacy, and PCI-DSS compliance
End-to-end ownership — own the full lifecycle of features, from technical design and implementation to monitoring and correct operation in production
Technical excellence and collaboration — partner with Product, Compliance, and Business to turn real payment problems into elegant solutions, and shape the platform through code reviews, architecture decisions, and clean, well-tested code

What Success Looks Like

Within your first 6–12 months, you own checkout services running payment flows in production, you've contributed to the event-driven architecture that keeps processing reliable at scale, and the team counts on your judgment in design and code reviews.

Skills You Need

Minimum Qualifications

5+ years of professional backend development experience
Strong proficiency in a modern, statically-typed backend language (our core stack is Kotlin and Go)
Deep expertise with payment processing concepts
Solid understanding of microservices architectures, including building and operating them in production
Relational databases (PostgreSQL or similar) and data modeling for financial systems
Containerization and cloud infrastructure (Docker, Kubernetes, AWS or GCP)
Strong command of unit, integration, and contract testing
English — fluent written and verbal

Preferred Qualifications

Experience with Kotlin and/or Go (Golang) — our core backend stack — and Spring Boot / WebFlux
Experience in a fintech, neobank, or payment orchestration environment
Hands-on experience with Kafka or other event streaming platforms
Familiarity with PCI-DSS, PSD2, or 3DS authentication frameworks
Observability tooling such as Datadog, OpenTelemetry, or distributed tracing

Nice to Have

Knowledge of network tokenization, smart routing, or payment optimization strategies
Prior work at a high-growth startup operating across multiple markets
Spanish proficiency