Senior Backend Developer (Services)

payabl.

23h•Remote

About The Position

payabl. empowers businesses to grow through payments innovation and banking services. Our ambition is to expand our strong portfolio of global financial services and make them all accessible through our unified platform, payabl.one. As a licensed financial company with principal membership with card schemes, we specialize in global payments and multi-currency banking solutions. The role is about: We are looking for a Senior Python Backend Developer (Services) to join our engineering team and contribute to the evolution of our service layer architecture. This role is focused on designing and building reliable, scalable microservices while also working with and gradually transforming legacy systems. You will play a key role in extracting business logic from existing codebases and reimplementing it into modern, maintainable Python services. This is a hands-on engineering role requiring strong problem-solving skills, attention to detail, and a deep understanding of backend systems reliability. Success in this role means going beyond “it works” — ensuring correctness, resilience, and long-term maintainability.

Requirements

5+ years of backend development experience with strong Python expertise
Deep knowledge of AsyncIO and FastAPI
Experience building non-blocking, high-reliability microservices
Strong experience with relational databases (MySQL, PostgreSQL)
Solid understanding of API design and third-party integrations
Experience implementing webhooks, callbacks, and retry strategies
Strong testing practices (unit and integration testing)
Ability to work with legacy systems and migrate them into modern architectures
Strong analytical and problem-solving skills
Ownership mindset and ability to work autonomously within a defined architecture

Nice To Haves

Experience with PHP, Perl, or JavaScript
Familiarity with Kafka, Redis, or event-driven architectures
Exposure to CI/CD pipelines, Docker, and Kubernetes
Experience in fintech, payments, or e-commerce domains
Knowledge of 3DS, tokenization, or payment gateway integrations
Proven experience migrating systems across technologies or paradigms

Responsibilities

Design, build, and maintain high-performance Python microservices (FastAPI, AsyncIO)
Analyze legacy systems and extract business logic into modern architectures
Refactor and migrate existing modules into clean, scalable, and maintainable services
Ensure system reliability through idempotency, fault tolerance, and robust error handling
Design and integrate external APIs, handling edge cases, retries, and failures
Implement and manage webhooks, callbacks, and complex retry mechanisms
Write high-quality unit and integration tests
Collaborate with cross-functional teams to ensure service stability and performance
Contribute to architectural discussions and continuous system improvements
Take ownership of services end-to-end, from design to production