Senior Kotlin Backend Engineer – FinTech (Remote, Flexible)

Fintech Core; Wilmington (NC); Remote; USD 140,000 - 180,000; Full time

Benefits offered by this job

Remote work mode

Flexible work schedule

20 billable days off in the first year

Ability to transfer unused vacation to

Job summary

Fintech Core is seeking a Senior Kotlin Backend Engineer to join an outsourced team working on a production-ready financial platform for business accounting and financial management. You’ll extend and improve the system, focusing on banking integrations, transaction processing, reconciliation, and analytics within an event-driven stack.

You’ll collaborate with client engineers to quickly onboard to the existing codebase, ensuring reliable backend delivery in a complex financial domain.

Qualifications

• 5+ years of backend development with production Kotlin experience
• Strong experience with REST APIs and maintainable service design
• Strong SQL, data modeling, and database performance skills
• Hands-on experience with messaging or event-driven architectures
• Understanding of distributed-systems challenges: idempotency, retries, duplicate messages, concurrency, eventual consistency
• Experience with automated testing, Git, code reviews, and CI/CD
• Understanding of authentication, authorization, and secure handling of sensitive data
• Ability to work independently in an existing codebase
• Experience in FinTech, banking, accounting, or payment systems
• English B2/C1

Responsibilities

• Backend development: extend the Kotlin Backend-for-Frontend (BFF) layer with APIs and business logic for new financial features
• Design REST APIs contract-first using OpenAPI
• Integrate new functionality into the existing architecture without breaking current behavior
• Support integration between Kotlin services, TypeScript/NestJS services, and external systems
• Build and extend integrations with banking providers (account connections, transaction imports, balance sync) and accounting systems, including Odoo
• Develop transaction-processing and reconciliation workflows that handle partial payments, duplicates, retries, and concurrency
• Implement event-driven communication (event contracts, consumers, transactional outbox) and scheduled or async workflows
• Ensure data consistency across APIs, services, and analytics
• Implement tenant-aware authorization and access control
• Apply idempotency, safe retries, version checks, and proper transaction boundaries
• Improve observability through logging, metrics, health checks, and alerts
• Investigate production issues and implement sustainable fixes
• Write clean, testable code with unit, integration, and regression tests
• Participate in code reviews, CI/CD, and documentation of APIs and architecture
• Take features from technical analysis to release, working with BA, PM, QA, frontend, and client team
• Identify risks and dependencies early and communicate estimates and options clearly

Skills

Kotlin & JVM

REST APIs

SQL/Data modeling

Event-driven

CI/CD & Git

Security awareness

English proficiency

Tools

Docker

Kubernetes

OpenAPI

Job description

Fintech Core is seeking a Senior Kotlin Backend Engineer to join an outsourced team working on a production-ready financial platform for business accounting and financial management. You’ll extend and improve the system, focusing on banking integrations, transaction processing, reconciliation, and analytics within an event-driven stack.

You’ll collaborate with client engineers to quickly onboard to the existing codebase, ensuring reliable backend delivery in a complex financial domain.