Top Senior Software Engineer Jobs in St. Louis, MO

Design, architect, implement, and test simulation software and virtual environments for flight trainers. Lead integration, validation, and documentation of simulation models, mentor junior engineers, support proposals, and work within agile teams to deliver simulation subsystems and tooling for training systems.

Develop and maintain simulation environments, test tools, and automation for F-22 avionics labs. Collaborate with lab partners and cross-functional teams to design, validate, and integrate simulation models, perform V&V, collect/process data, and modernize legacy systems while supporting hardware/software integration and test infrastructure.

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 non-embedded software for the Tomahawk program. Translate requirements into software designs, implement features, troubleshoot issues, and document R&D. Ensure compliance with government and safety standards and support system integrations.

Senior Software Engineer responsible for owning and supporting the MCA international cash management platform. Duties include COBOL development, mainframe application support, Oracle Database and Linux administration, monitoring with Dynatrace, incident and change management via ServiceNow, vendor coordination (including Oracle Flexcube), troubleshooting production issues, delivering enhancements, and participating in Agile delivery to ensure platform reliability and regulatory compliance.

The role involves leading application performance improvements across multiple platforms, focusing on measurable metrics and driving engineering standards and workflow optimization, using both hands-on coding and strategic influence.

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.

Lead UI architecture and design for responsive web applications; build reusable components with Angular/React/Vue and TypeScript/JavaScript; integrate UIs with RESTful microservices; enforce accessibility, security, testing, and CI/CD standards; mentor developers and collaborate with UX, backend, and DevOps teams in Agile environments.

Design and implement CIAM backend services for authentication and authorization. Integrate identity systems, manage secure flows, and automate infrastructure.

The role involves developing and optimizing React Native applications, integrating AI capabilities, and collaborating with cross-functional teams to deliver innovative mobile experiences.

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.

Design, implement, and operate large-scale distributed storage systems ensuring data durability, availability, and performance. Build and maintain replication, erasure coding, and lifecycle systems; write high-quality Go/Rust/C++ code; participate in on-call rotations; troubleshoot production incidents; collaborate with networking, hardware, and capacity teams; lead scoped projects and drive infrastructure evolution.

As a Billing & Analytics Software Engineer, you'll design and maintain the billing pipeline, integrate billing systems, and develop customer-facing analytics dashboards to support revenue recognition and operational observability.

Lead design and delivery of scalable customer-facing features, services, and APIs that process real-time data and AI-powered insights. Build web experiences, contribute to LLM/AI workflows, ensure reliability through observability and rollout practices, and collaborate cross-functionally with Product, Design, ML, and platform teams.

Lead architecture, modernization, and development of Group Insurance applications. Modernize mainframe monoliths into Java microservices and micro-frontends on cloud, mentor distributed Agile teams, collaborate with enterprise architecture, product owners and infrastructure, and enable test automation and integrations. Approximately 10% domestic travel.

Lead frontend-leaning full-stack implementation work for carrier and enterprise integrations: architect reusable UI and API layers, author RFCs, guide technical delivery, enforce testing and security best practices, and partner with cross-functional teams to scope and ship production integrations.

Design and develop complex software solutions for the FedNow service, leveraging cloud technologies, Java, and Agile methodologies, ensuring high-quality and timely infrastructure support.

Build and own Eve's marketing site and GTM engineering stack: integrate and optimize external tools, design AI agents for sales and marketing, implement webhooks and middleware to sync product/CRM data, and create programmatic campaigns and internal tools in partnership with Marketing, Sales, RevOps, and Product to drive growth and automation.

As a Senior Software Engineer in Trust & Safety, you'll analyze threats, design systems for abuse detection, and collaborate with teams to implement scalable defenses.

Design, build, and maintain scalable, reliable full‑stack systems. Contribute to API and architecture design, write testable code, debug complex issues, improve performance, automate deployments, and mentor junior engineers while collaborating with cross‑functional teams.

As a Software Engineer, you will design, develop, and integrate capabilities in a complex system while collaborating with team members to deliver impactful solutions.

Lead and manage a team of software verification engineers to design, develop, and execute requirements-based test plans and automated test frameworks. Perform functional, performance, and safety verification, report defects, and support formal qualification testing. Coordinate with program management, systems engineers, and developers in an Agile, CI/CD-driven environment for defense flight systems.

Design, develop, test, and maintain non-embedded Tomahawk software across the lifecycle. Perform MBSE, manage requirements and CRs, develop architectures, unit test and integrate components, create verification plans, and mentor junior engineers while ensuring DoD and export-control compliance.

Design, build, and maintain web application infrastructure and data systems for interactive information experiences. Lead application architecture, code quality, performance, and reliability; integrate generative AI and prototype XR interfaces; collaborate with designers and data scientists; ensure security, accessibility, scalability, and document technical standards.

Develop, test, and maintain web-based geospatial intelligence applications using Java/Python. Design features, integrate relational and NoSQL data, apply secure coding, participate in Agile sprints, code reviews, and CI/CD. Support performance tuning, documentation, and mentor junior developers in a classified environment.