Sr. Software Engineer (Scala)

NinjaTrader•Chicago, IL

10d•$125,000 - $175,000•Hybrid

About The Position

We are seeking a Sr. Software Engineer to join our Evaluation Services team. Our Evaluation Services business powers funded trader programs that give aspiring traders a pathway to professional trading capital. You will design, build, and maintain the Scala-based backend systems that power our auto-liquidation engine, risk evaluation, and trading services—the core systems our platform and partners depend on. You will own complex backend problems end-to-end and work alongside Trading Services Engineers, frontend engineers, QA, and solutions engineers to deliver high-quality, production-ready features in a fast-paced environment.

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

Nice To Haves

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

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