Principal Software Engineer, Platform Engineering

Principal Software Engineer- Platform Engineering ​​Remote, United States JOB OVERVIEW We are seeking a Principal Software Engineer to serve as a technical force-multiplier on Legion's Platform Engineering Team — the backbone of our multi-tenant SaaS application. As a Principal, you independently own significant platform domains, drive architectural decisions that span multiple teams, and elevate the engineering capability of everyone around you. This role is fundamentally about software engineering at scale. You will design and build the core platform services, APIs, and data systems that power Legion's product. You remain deeply hands-on — writing and reviewing production code — while operating with the judgment and autonomy of a staff-level engineer. You are a builder first. RESPONSIBILITIES AND DUTIES Technical domain ownership Own the design, implementation, and evolution of one or more core platform domains — such as multi-tenancy, API framework, job processing, data pipelines, or platform SDK/extension points. Lead end-to-end software design for significant new capabilities, from technical specification through production delivery and long-term maintainability. Proactively identify and resolve scalability, correctness, and security issues in platform code and data models before they reach production. Drive data modeling, API design, and service decomposition decisions for high-concurrency, enterprise-scale workloads. Actively use GenAI coding tools (GitHub Copilot, Cursor, Claude Code) as a standard part of your software development workflow — demonstrated prior use required. Establish team-wide best practices for AI-assisted development and code review. Cross-team technical leadership Produce and champion design docs that establish engineering patterns adopted across Platform and adjacent product teams. Lead design reviews for complex systems built by senior and mid-level engineers; provide structured, high-signal feedback that improves both the design and the engineer. Partner closely with architects to translate long-term strategy into well-sequenced, concrete engineering work. Collaborate cross-functionally with Product, QA, and Data Engineering to align software design with product and operational requirements. Code quality and engineering standards Define and uphold coding standards, testing practices, and API design conventions for the Platform team. Drive initiatives that measurably improve platform reliability and developer experience through better software design — not just tooling or process. Lead post-mortems for significant production issues with a focus on durable software fixes, not operational workarounds. Participate in on-call rotation; serve as the senior escalation point for complex production issues requiring deep code-level diagnosis. Mentorship and talent development Actively mentor Engineers through technical pairing, design feedback, and structured growth conversations. Identify and close skill gaps on the team through knowledge-sharing, internal documentation, and architectural walkthroughs. Contribute to hiring: define the technical bar, design engineering interview problems, and provide substantive written debrief feedback. REQUIRED SKILLS AND QUALIFICATIONS 8–12 years of experience designing and building backend or platform software for enterprise SaaS or cloud-native applications, with a primary focus on application-layer engineering, not infrastructure operations. Deep expertise in Java, Spring Boot, Hibernate, MySQL, and RESTful API design — demonstrated through architecting complex, high-throughput production systems. 5+ years working in cloud environments (AWS preferred); strong understanding of how cloud services affect software design, performance, and cost — not just how to configure them. Demonstrated experience independently driving multi-team software design decisions: writing design docs, facilitating alignment, and managing technical tradeoffs. S ... (truncated, view full listing at source)