Top Senior Software Engineer Jobs in St. Louis, MO

As a Staff Software Engineer, you'll develop and maintain core platform infrastructure, design scalable systems, mentor junior engineers, and ensure reliability of product features.

Lead technical strategy and execution for enterprise software, design and build new systems, improve existing platforms, mentor engineers, collaborate with product and stakeholders, ensure quality/performance, share best practices, analyze costs, and support operational readiness including on-call production support.

The Staff Software Engineer will lead projects, mentor team members, write code using Python, Django, React, JavaScript, and TypeScript, and impact the healthcare system with software solutions.

As a Senior Software Engineer at Medallion, you'll lead projects, mentor team members, and work with technologies like Python, Django, React, and TypeScript to impact healthcare operations.

Design, develop, and maintain scalable full-stack web applications. Build reusable UI components, develop backend services and APIs, contribute to architecture, participate in code reviews, mentor peers, collaborate cross-functionally, and reduce technical debt while ensuring high performance and maintainability.

Design and build core LLM platform primitives, safety and observability infrastructure, provider abstraction and evaluation systems, prompt lifecycle and Agent-as-a-Service; collaborate with product teams, document reference implementations, and lead technical standards to enable other engineers to build production AI features.

Build and deliver end-to-end features across backend APIs (NestJS/TypeScript) and frontend interfaces (React/TypeScript), integrate third-party services, own production services (on-call, monitoring, incident response with Datadog), contribute to architecture, and mentor other engineers. Work across web and React Native mobile apps, and help scale integrations and event-driven systems.

Design and scale distributed systems for Ditto's edge-to-cloud capabilities, lead services development in Rust, and mentor engineers.

Build and own a framework-agnostic charting engine core and its React binding: rendering layers, real-time data plumbing, indicator math, drawing tools, performance (60fps) discipline, visual testing, architectural leadership, mentoring, and integrations across web and mobile.

Lead architecture and evolution of Juniper Square’s distributed services, cloud infrastructure, and developer platform. Design scalable, multi-tenant, event-driven systems; build paved-road developer tooling, CI/CD, and observability. Hands-on coding, prototyping, and performance troubleshooting. Enable production AI/LLM workloads, ensure security/compliance, support enterprise upmarket needs, and mentor engineering teams to raise operational excellence and reliability.

As a Senior Software Engineer, you'll design and maintain frontend applications and reusable components, integrate APIs, mentor engineers, and ensure high-quality user experiences in the fintech space.

As a Senior Software Engineer at Flex, you'll design and maintain financial services architecture, mentor junior engineers, and ensure scalability and security for innovative financial products.

Design, build, and operate full‑stack features and platforms for Horizon. Work across frontend, backend, infrastructure, data, and developer tooling; formulate solutions, ship production code, improve reliability and developer productivity, and expand AI/agent-assisted workflows. Collaborate with product, customers, and cross-functional teams, review code (including agent-generated), and improve internal tooling, observability, and deployment workflows.

Develop and maintain a digital ordering platform for medical equipment. Lead technical decisions, deliver quality code, and ensure system reliability while collaborating in an agile environment.

The Senior Software Engineer will architect and optimize AI-powered developer tools, enhance the SDLC, collaborate across teams, and mentor peers to improve engineering productivity.

Build and improve the end-to-end experience for new customers by implementing features across Python services, a GraphQL gateway, Auth0-based auth, and Terraform-managed GCP infrastructure. Collaborate cross-functionally to redesign discovery, evaluation, onboarding, and time-to-value while ensuring reliability, testing, and stable deployments.

Lead design, development, and maintenance of cloud hosting management and orchestration solutions. Mentor engineers, review code for quality and security, design REST APIs, troubleshoot issues, improve performance and reliability, and drive requirements and architecture decisions to enhance customer experience.

Lead backend development using C#/.NET and cloud-native technologies. Build and maintain APIs, ensure quality and performance, troubleshoot issues, conduct code reviews, and drive software/process improvements.

Build and operate backend systems enabling enterprise deployments of Coder. Design and implement scalable backend architecture, improve upgrade and migration reliability, investigate and resolve production scalability issues, own operator-facing backend features, document tradeoffs, participate in design reviews and on-call rotations.

Lead design, implementation, and operation of production-quality DevOps platforms and automated test infrastructure for heterogeneous edge hardware. Improve CI/CD, build/release, deployment automation, developer tooling, and platform reliability. Enable reproducible tests, diagnose failures across devices, partner with engineering and QA, and drive major infrastructure initiatives from ambiguity to production.

Design, build, and own the Fastpath Assure connector for NetSuite (primary) and Oracle EBS/Cloud. Develop SuiteScript, saved searches, data extraction logic, and PL/SQL integration components. Drive roadmap, troubleshoot customer environments, collaborate with product and engineering, mentor engineers, and contribute customer-facing content and webinars.

Design and build cloud-native, highly available systems and serverless applications on Azure. Implement Infrastructure-as-Code, develop TypeScript/React/NestJS applications, create APIs for web/mobile/IoT, write automated tests, deploy frequently, and participate in production support and on-call rotations while working in agile teams.

Senior individual contributor responsible for designing and building complex, customer-facing product features. Own technical decisions within product areas, collaborate with Product and Design, contribute to architecture, maintain code quality, mentor engineers, and participate in production support.

Design, build, and launch backend services to process and analyze clinical data at scale. Collaborate cross-functionally, enforce secure coding and privacy, support production systems, and drive technical improvements.

Senior Java engineer responsible for designing, developing, and maintaining scalable, secure backend systems using Java and modern frameworks. Participate in architecture, collaborate with product and security teams, write maintainable code, and adopt AI-assisted development tools while contributing to open-source efforts.