Sr. Software Engineer (Scala)

NinjaTrader is an industry-leading trading platform and futures broker empowering traders to take control of their financial destiny. They are seeking a Senior Software Engineer to design, build, and maintain Scala-based backend systems that support their evaluation services and trading capital programs.

Responsibilities:

• Design and implement backend services in Scala for evaluation, risk, and trading service workloads, including real-time auto-liquidation, account state management, and post-trade processing
• Build and evolve actor-based systems, such as Akka or similar technologies, that handle high-throughput market data, position changes, and event-driven workflows
• Own significant features end-to-end, from technical specifications through implementation, code review, and production handoff
• Design data models and database changes in PostgreSQL, including JSONB where appropriate, and contribute to the shared master schema, Protobuf, and SQL repositories
• Diagnose and resolve complex backend issues, including production incidents, by analyzing logs, tracing distributed flows, and reproducing edge cases under realistic loads
• Drive code quality across the team through thorough pull request reviews, clear acceptance criteria, disciplined development testing, and proper instrumentation and observability
• Collaborate with Trading Services, Solutions Engineering, and Product to translate business requirements into well-scoped, accurately estimated stories
• Contribute to architectural decisions and long-term technical debt remediation, including modernizing legacy Scala services and evaluating new event bus technologies
• Mentor junior team members on Scala idioms, functional design, testing practices, and incident response
• Develop deep expertise in NinjaTrader’s evaluation platform and partner integrations to provide authoritative backend leadership

Requirements:

• 5+ years of backend software engineering experience building production systems that handle real-time data, concurrency, and high availability
• Strong, hands-on Scala expertise, including idiomatic Scala, functional patterns, testing with ScalaTest or similar tools, and comfort working in a large, existing Scala codebase
• Experience with actor-based concurrency models, such as Akka, Pekko, or equivalent technologies, including an understanding of supervision, message passing, and backpressure
• Solid relational database skills with PostgreSQL, including schema design, indexing, query optimization, and sound judgment about when to use JSONB versus a normalized structure
• Comfort with event-driven architectures, message buses such as Kafka or Pub/Sub, and asynchronous workflows
• Excellent troubleshooting skills, with the ability to read logs, trace requests across distributed systems, and isolate root causes under pressure
• Demonstrated ability to write clear technical specifications, scope work realistically, and identify risks early
• High standards for code, tests, documentation, and pull requests, along with a willingness to uphold those standards during code reviews
• Ability to think on your feet and adapt quickly when priorities shift or unexpected issues arise
• Outstanding written and verbal communication skills, with the ability to explain backend tradeoffs to technical and non-technical audiences
• Self-starter who thrives in ambiguity and can manage multiple complex backend initiatives simultaneously
• Experience with trading platforms, fintech, or capital markets technology
• Understanding of trading concepts, including order routing, market data, position management, risk and liquidation logic, and profit and loss calculations
• Familiarity with Protobuf, gRPC, or schema-based service contracts
• Experience migrating or modernizing legacy Scala systems or evaluating transitions from Scala to Rust or Go
• Background in observability, including distributed tracing, structured logging, and metrics using Datadog, Google Cloud Platform, or similar technologies
• Prior experience supporting enterprise or business-to-business partner integrations