Top Senior Software Engineer Jobs in St. Louis, MO

Develops and leads software design, coding, testing, integration, requirements traceability, code reviews, verification, and deployment for Boeing Phantom Works solutions. The role collaborates with stakeholders, resolves technical risks, evaluates team and supplier performance, and mentors junior engineers. Work involves Java or C++, MATLAB, DevSecOps tools, Agile development, and complex space-based mission applications. An active Top Secret clearance and U.S. person status are required.

Design, architect, and develop simulation models, virtual environments, and frameworks. Validate, integrate, modernize, and test simulation software and legacy systems, collect and process data, document algorithms and specifications, and collaborate with cross-functional teams to enable system integration and optimize performance in a secure Agile environment.

Lead design and implementation of backend systems for Model-Based Engineering web applications. Build APIs, data-processing and analytics pipelines, optimize SQL, develop production-ready infrastructure, create test suites, mentor engineers, participate in architecture and tech selection, and ensure scalability, resilience, and performance for large-scale distributed systems.

Design, develop, test, and maintain embedded application software for air-domain missions. Translate customer requirements into software architecture, perform unit/integration testing, support system integration and verification, participate in peer reviews, and produce software documentation while meeting safety, regulatory, and customer standards.

Design, develop, test, and maintain embedded software for weapons programs. Translate requirements into designs, develop interfaces, perform unit/integration testing, support system integration, participate in peer reviews, and create documentation while meeting safety, security, and regulatory standards.

Develops, integrates, tests, maintains, and troubleshoots mission-planning software for defense systems. Translates customer requirements into software designs, supports architectures and system integrations, resolves technical issues, and improves software processes within Agile environments. The role requires C# and .NET development, version control experience, U.S. citizenship, and eligibility to obtain a Secret clearance.

Leads performance engineering across the organization by designing load-testing and data-generation frameworks, defining benchmarks and standards, analyzing application, database, and system behavior, and guiding teams in performance optimization. Builds reusable tooling and best practices using k6, JavaScript, Grafana, and InfluxDB while addressing scalability, latency, throughput, and reliability challenges in distributed cloud-native systems.

Designs, develops, tests, integrates, debugs, and sustains non-embedded software for military platform health management systems. Translates customer requirements into software architectures and implementations, supports CI/CD and Agile development, manages interfaces and documentation, troubleshoots user issues, improves software processes, and contributes to research, project management, supplier oversight, compliance, and certification activities.

Develop, test, and maintain mission-planning weapon software within a SAFe Agile scrum team. Translate requirements into designs, implement and integrate microservices (C#/C++ back end, JavaScript/TypeScript/React front end), debug issues, write documentation, and perform unit/integration/system-level testing and validation.

Develop and deploy customer-focused web, mobile, and backend applications across the full software stack. Design major features, contribute to architecture decisions, conduct code reviews, and ensure secure, high-quality implementations. Collaborate with stakeholders and cross-functional teams using Agile and SDLC practices. Manage version control, CI/CD, environments, and releases; maintain automated test coverage and perform root-cause analysis. Build and optimize relational data solutions using SQL Server, including complex queries, stored procedures, and performance tuning.

Design, build, deploy, and support scalable Java microservices on AWS. Provide technical leadership, architectural direction, code reviews, troubleshooting, proof-of-concept development, and cross-functional collaboration. Work with high-throughput data, messaging systems, distributed architectures, observability, and AI-assisted development tools. Participate in on-call support, mentor engineers, lead architectural initiatives, and deliver reliable SaaS platform features.

Leads software testing for Boeing mission systems, developing test plans, verification procedures, test environments, and testing strategies across emulation, simulation, development kits, and hardware. Ensures requirements compliance, safety- and mission-critical testing, software process adherence, and coordination across technical and systems teams. Executes and documents testing, supports research and development projects, and mentors other engineers. The role is fully onsite in Berkeley, Missouri, and requires an active Secret clearance and U.S. citizenship.

Own the development and maintenance of large-scale React Native applications for iOS and Android. Lead architecture improvements, React Native upgrades, native module development, performance optimization, automated testing, CI/CD reliability, and production debugging. Collaborate with cross-functional product pods, contribute to technical discovery and architecture, mentor engineers, and raise engineering standards while delivering scalable, maintainable mobile experiences.

Lead design, development, testing, debugging, and maintenance of embedded software for vehicle health management on air vehicle/avionics systems. Translate customer requirements into software designs, integrate software with specialized hardware, improve system efficiency and stability, guide testing and adoption of emerging tools, and oversee supplier and internal team performance and embedded software project management.

Design, build, and operate foundational developer infrastructure across CI, build systems, deployment orchestration, and test platforms. Improve build speed, deployment safety, and test reliability while owning services end to end, including SLOs, observability, and on-call responsibilities. Partner with engineering teams to address platform pain points and lead cross-cutting technical projects through production.

Lead Software Engineer responsible for software design and development for defense-related projects, mentoring junior engineers, and ensuring project alignment with requirements and standards.

Develops and supports automated software testing infrastructure for avionics and Open Mission Systems software. Responsibilities include designing testing frameworks, AI/ML and computer vision solutions for automated Pilot/Vehicle Interface testing, embedded software integration and debugging, requirements collaboration, and maintaining compliant software solutions. The role is fully onsite, supports agile development, and requires adherence to government, safety, export-control, and industry standards.

Develop and administer STIBO STEP solutions supporting enterprise master data management initiatives. Responsibilities include designing workflows, WebUI interfaces, attributes, validation rules, and integrations; ensuring data quality, governance, and platform performance; troubleshooting complex issues; supporting production operations and SaaS upgrades; and collaborating with Product, stakeholders, and engineering leadership. The role also includes mentoring engineers, estimating work, driving delivery, and implementing product, vendor, and customer data governance frameworks.

Lead technical strategy and execution for foundational Trust and Safety systems supporting consumer risk and credit reporting. Design and operate highly available backend systems, improve reliability and monitoring, establish engineering standards, guide complex cross-functional initiatives, and mentor engineers. The role involves ownership of system architecture, technical planning, operational readiness, code quality, and team development.

Develop scalable C++ software that defines and enforces endpoint behavior across millions of managed Windows endpoints. Responsibilities include implementing features, improving platform performance, shipping production code, designing new systems, writing architecture documents, defining subsystem contracts, and collaborating with server, UI, product, and design teams. The role requires deep Windows systems and kernel-driver expertise, with preferred experience in WHQL, minifilter or WFP drivers, macOS Endpoint Security, and Linux kernel development.

Lead the design, development, and delivery of scalable payroll onboarding software. Drive technically complex initiatives, influence architecture and roadmaps, collaborate across product, design, and engineering, improve reliability, promote coding best practices, mentor engineers, and use AI tools to enhance development productivity.

Build and ship production software for Toast’s retail platform, partnering with engineering, product, and customers. Responsibilities include identifying opportunities, designing and prototyping end-to-end solutions, making foundational technical decisions, incorporating customer feedback, tracking industry trends, and deploying AI-powered experiences. The role supports large grocery and convenience-store customers and may involve visiting stores to understand operator workflows.

Build and scale the PSA Liquidity Platform connecting buyers and sellers across PSA Partner Offers and eBay Consignment. Responsibilities include developing buyer tooling, pricing and ranking engines, seller experiences, microservices, distributed event-driven systems, and observability. The role owns end-to-end product delivery, cross-functional execution, technical architecture, ecosystem integrations, and production outcomes while using AI throughout the software development lifecycle.

Develop and maintain scalable Java and Spring Boot REST services, APIs, and microservices for mission-critical geospatial systems. Support containerization, orchestration, CI/CD, DevOps automation, testing, infrastructure deployment, data platforms, and third-party integrations. Contribute to architecture, performance optimization, troubleshooting, documentation, stakeholder demos, and Agile delivery. The role requires onsite work in Herndon, Virginia and collaboration on national security missions.

Build and own full-stack services and APIs enabling businesses to offer and manage 401(k) plans. Design scalable features, evolve system architecture, establish engineering best practices, collaborate with product, design, compliance, and operations, debug production issues, and improve reliability, observability, and operational tooling. The role requires end-to-end system ownership, production support, and cross-team technical influence.