Simulmedia is seeking an experienced Senior Backend Engineer to join our engineering team, working on the backend and data infrastructure powering our TV advertising platform - spanning National Linear and CTV. This role sits within a distributed system of up to ~30 microservices, and you'll be primarily responsible for building, scaling, and operating backend services - with secondary exposure to backend-for-frontend work in TypeScript/Node. In this role you will work closely with product managers, designers, and data engineers to ensure seamless integration of analytics features into the platform. The ability to frequently iterate and deliver high-quality features that are owned end-to-end is crucial in this role. We're looking for someone who takes ownership, communicates directly and honestly, and cares about the reliability and craft of the systems they build - not just shipping features but understanding how they behave in production. Location: Ukraine is mandatory. Our offices are located in Kyiv and Lviv. Teams are located in Kyiv and Lviv and primarily work remotely with occasional offline meetings. Key Responsibilities: Design, build, and maintain backend services in Ruby (Roda) operating within a large-scale distributed microservice architecture. Contribute to backend-focused TypeScript/Node.js work, including API design and tRPC procedures, in support of Next.js applications. Own service reliability: instrumentation, monitoring, and observability across services (tracing, metrics, structured logging). Collaborate closely with data engineers on data pipelines, ETL processes, and ensuring clean, well-modeled data flows between services. Investigate and resolve production incidents; contribute to and follow oncall/runbook practices. Design and evolve APIs with strong attention to authentication, authorization, and security best practices. Participate in code reviews, pair programming, and knowledge-sharing sessions to ensure high-quality, maintainable code. Write thorough unit and integration tests for backend services Work independently while communicating clearly across a distributed, cross-functional team Qualifications: Bachelor’s degree in Computer Science, Computer Engineering, or a related technical field. 5+ years of professional Ruby backend development experience; prior experience may be with Rails, Roda, Sinatra, or similar - deep Roda-specific knowledge is not required, as long as the underlying Ruby fundamentals are strong. Experience operating within a distributed systems / microservice architecture. Solid working knowledge of observability tooling - OpenTelemetry, Datadog, Grafana, Prometheus, or equivalent - including setting up tracing, metrics, and alerting, not just consuming dashboards. Experience with error tracking/monitoring tools such as Sentry, Honeybadger or equivalent. Hands-on experience in TypeScript and Node.js, with practical experience in Next.js for backend/API-layer work. Experience with tRPC or comparable typed API frameworks. Solid experience with AWS and its core services (e.g. EC2, S3, RDS, SQS/SNS, ECS/EKS), including infrastructure-as-code with AWS CDK, plus containerized applications (Docker). Experience designing and evolving APIs, including auth, security, and versioning concerns. Experience working in a large distributed system with dozens of independent services, potentially written in different languages; ability to quickly get up to speed in unfamiliar code and trace a request's path across multiple services end-to-end. Experience with CI/CD pipelines - we currently use Jenkins and are actively migrating to GitHub Actions, so comfort with either (and ideally migration experience) is valuable. Ability to use AI coding tools (e.g. Claude Code, Codex, Cursor, or similar) effectively to speed up development, debugging, and code comprehension. Strong communication skills; ability to work independently and take ownership of services end-to-end. Ability to communicate effectively with the U.S.-based teams and work 11:00 AM - 8:00 PM EEST (11:00 - 20:00). Bonus Points for: Python experience (data tooling, scripting, or services) Experience in AdTech or digital advertising/media analytics Prior experience in a service migration, decomposition, or platform-modernization effort Interview Process Pre-screening (30 mins) Technical Interview (1h) System Design (1.5h) Product Interview (30 mins) Offer