RoR software engineer in fintech

Aristek Systems is actively involved in the development of innovative IT solutions for the US and European markets. Our team consists of over 170 highly qualified professionals of various IT-spheres. Now we are looking for a Middle Ruby (RoR) Software Engineer to join our team! Fintech platform that integrates multiple financial services into a single product.

• Develop and maintain backend services of a fintech platform (fiat/crypto payments, wallets, ledger, KYC).
• Build and evolve REST APIs (Rails 8 API-only), keeping the OpenAPI specification in sync.
• Integrate with third-party financial services: crypto exchange, KYC provider, banking/SEPA, SMS and messaging providers.
• Implement background processing and scheduled jobs (Sidekiq, sidekiq-scheduler).
• Write automated tests (RSpec) for every change, including edge cases and idempotency.
• Perform code reviews and keep technical documentation up to date.
• Collaborate with Frontend (React), BA, QA and DevOps.
• Participating in daily meetings and plannings.

• 3+ years of commercial experience with Ruby on Rails
• Experience with modern Rails (7/8) API-only applications
• Strong RSpec skills (FactoryBot, WebMock, request and service specs)
• Solid experience with PostgreSQL and Redis
• Experience with Sidekiq and background job processing
• Experience integrating third-party APIs (Faraday/RestClient, webhooks, error handling, retries)
• Understanding of authentication and authorization (JWT, OAuth2/Doorkeeper)
• Experience with Docker and Git (GitLab)
• Understanding of database transactions, data consistency and idempotency
• Ability to quickly understand business requirements and deliver working, production-ready solutions in a fast-paced environment
• English B1+.
• Будет плюсом: Experience in fintech, payments or crypto (exchanges, wallets, ledgers, KYC/AML); Experience with microservice / service-oriented architecture; OpenAPI / Swagger (rswag); Observability: OpenTelemetry, Prometheus, structured logging; Security tooling and practices (Brakeman, rate limiting, secure handling of financial data); Basic knowledge of React.js and TypeScript; Experience with AI-assisted development tools (Claude Code, Cursor)

• Ability to work fully remote
• 20 paid days per calendar year for vacation
• 3 paid days per calendar year, allowing temporary absence of an employee for medical reasons without sick leave
• Partial payment for medical insurance
• Partial payment for a monthly gym membership card
• Payment of 50% of the cost of a partner service for learning English
• English Paired Classes with a certified teacher
• English Speaking Club with a certified teacher
• Team buildings, corporate parties and other extracurricular events
• Gifts in case of important events in your life (birthday/wedding/the birth of a child)
• Partial payment of advanced trainings, conferences and educational courses
• 50% payment of Spotify Premium
• Pay 50% of the cost of the affiliate service, which gives access to more than 250,000 books
• Partial compensation for a laptop purchase
• Referral program
• Knowledge base
• Inhouse learning and development manager.