Top Senior Software Engineer Jobs in St. Louis, MO

Design, develop, and deploy Python- and Java-based scalable REST APIs for a multi-tenant web platform. Collaborate with product, data science, and clinical partners, and ensure software quality, security, and engineering best practices.

The Senior Software Engineer role involves developing enterprise applications using Java, JavaScript, or Python, managing databases, and providing support for geospatial information systems, among other responsibilities.

Contribute to high-performance, real-time applications processing critical financial data. Collaborate with teams, develop clean applications, and maintain testing strategies.

Design, build, and maintain scalable web applications, APIs, and backend services across multiple stacks. Make architectural decisions, remediate technical debt, lead client communication and demos, participate in agile teams and code reviews, uphold testing and debugging practices, and contribute to internal best practices and thought leadership.

Senior hands-on engineer owning Prebid/header-bidding wrapper and client-side monetization. Implement and maintain Prebid.js/Server integrations, optimize on-page performance/Core Web Vitals, work with GAM/GPT/IMA, deploy services on GCP, and ensure reliability at scale.

Join Twilio as a Staff Software Engineer to design and build scalable, reliable communication systems. Collaborate with cross-functional teams, mentor engineers, drive technical direction, perform architecture and code reviews, and deliver high-quality production services in a remote-first environment.

Own and evolve core trading platform services: design and build cloud-native .NET microservices, APIs, and high-availability distributed systems. Drive architecture, reliability, monitoring, incident response, and mentor engineers while occasionally contributing to React/TypeScript frontend work.

Lead design, development, and implementation of Salesforce solutions (LWC, Apex, Visualforce) including Experience and Commerce Cloud and Accounting Seed. Build integrations (REST/SOAP, payment gateways), CPQ and Marketplace apps, mentor developers, perform code reviews, and optimize platform performance and reliability.

Design, build, and maintain scalable brokerage systems including gRPC microservices and a React admin UI. Lead regional engineering initiatives, mentor engineers, act as incident commander, troubleshoot production issues, and collaborate with global teams to support multi-market growth.

Design, implement, and maintain scalable brokerage systems and middle/back-office services (gRPC microservices, React admin UI). Lead regional recruitment and reliability, mentor engineers, act as incident commander, collaborate with global teams, troubleshoot issues, and build solutions supporting multi-language/currency markets and regulatory requirements.

Lead design, implementation, and deployment of core platform tooling enabling secure, cloud-native application delivery. Integrate with defense systems, own architecture, mentor engineers, contribute to open source, maintain documentation, and participate in a shared 24x7 on-call rotation.

Lead modernization of internal platform tooling to 12-factor apps, delivering full-stack services (Go/Python + React/Vue), instrumenting observability (Grafana/Prometheus/Loki), driving Kubernetes-native GitOps (ArgoCD/GitLab CI), mentoring developers, and automating infrastructure with Ansible/Terraform on private/bare-metal clouds.

Lead architecture and technical strategy across an infrastructure platform ecosystem. Drive hands-on architectural improvements to graph engine and backend services, reduce technical debt, establish standards, champion AI-first engineering practices, run architecture/code reviews and mentorship, and collaborate with product and leadership to ensure scalable, extensible systems.

Design, develop, and maintain complex, enterprise-scale software features and services across the OneStream CPM platform. Lead technical design, implement UI and APIs, ensure JSON/XML contract compatibility, improve performance and reliability, mentor engineers, participate in code reviews, and support CI/CD, testing, and production operations. Use AI-assisted development tools responsibly to accelerate development.

Design, build, and scale backend systems and APIs for high-transaction consumer products. Collaborate with product, credit, compliance, support, and analytics teams. Contribute to code reviews, technical planning, security, and operational excellence. Mentor peers and promote engineering best practices.

Lead full‑stack modernization of a legacy .NET/SQL Server payment-integrity platform. Build modular Angular frontends and resilient .NET microservices, improve APIs, optimize database performance, embed security/privacy, use AI coding agents to accelerate refactors, and drive delivery with strong observability and testing practices.

Design, build, deploy, and operate backend services, APIs, integrations, and web applications. Own end-to-end features, improve CI/CD and observability, troubleshoot cross-service issues, participate on-call, and collaborate with product and leadership to deliver reliable production systems.

Design, build, and own large-scale distributed backend systems in Go to process billions of events and petabytes of data. Lead architecture, reliability, observability, and performance efforts; improve service communication and data pipelines; debug production at scale; mentor engineers and share learnings publicly.

Lead full-stack development using React, Node and TypeScript. Design scalable architecture, write and review code, ensure performance, accessibility and security, mentor off-shore teams, participate in Agile ceremonies, support production (including weekends/off-hours), and collaborate with cross-functional teams to deliver business-critical applications.

Lead and mentor engineering teams to design and deliver scalable, high-performance systems. Define technical roadmaps, set code quality standards, drive architecture and technical debt resolution, collaborate with Product and Design, make technology decisions, lead hiring and interviews, and research new tools to solve complex problems while advocating for engineering priorities and timely feature delivery.

Own and evolve high-scale backend and data-layer services. Design, build, test, and operate distributed backend services and APIs, improve reliability/latency/scale, take end-to-end ownership from design through production support, participate in on-call and incident response, and mentor peers while partnering with Product and SRE teams.

Design, develop, and maintain secure, scalable full-stack web applications across backend, APIs, and frontend. Collaborate with product and design, perform code reviews, mentor engineers, troubleshoot complex issues, and drive continuous improvement and AI-enabled solutions throughout the SDLC.

Build and operate Elastic Build and Melange to produce, validate, and deliver Chainguard OS packages. Improve reliability, scalability, automation, observability, and multi-architecture support; implement rebuild/review automation; run on-call, incident response, and document systems and roadmap.

As a Senior Software Engineer, you'll ship quality software across the web stack, collaborate with product/design teams, and provide technical leadership within a small engineering team.

The Senior Software Engineer will architect and develop the Solver network, ensuring performance, collaborating with teams, and leading engineering standards.