Top C# Jobs in St. Louis, MO

Develop and support enterprise B2B and B2C eCommerce solutions using .NET/C# and Optimizely Configured Commerce. Build commerce capabilities, integrations, APIs, and event-driven services; troubleshoot application and database issues; optimize performance, scalability, accessibility, and SEO; participate in code reviews; and collaborate with product, architecture, frontend, integration, and business teams.

Develop and maintain macOS systems software using modern C++, Swift, and Objective-C++. Work with process models, IPC, Endpoint Security, Network Extension, security and cryptography APIs, device and storage frameworks, packaging, deployment, and MDM tooling. Profile and debug performance using Instruments, LLDB, os_log, and os_signpost, while creating tests with XCTest, sanitizers, fuzzing, and xcodebuild CI. Support shared codebases across macOS, Windows, and Linux.

Develop and maintain cross-platform macOS systems software using modern C++, Swift, and Objective-C++. Work with IPC, daemons, system extensions, network and endpoint security, device and storage APIs, code signing, packaging, and deployment. Profile and debug performance issues, build automated tests and CI pipelines, and support Apple Silicon and Intel systems. Nice-to-have experience includes SwiftUI, AppKit, macOS beta testing, and shipping EDR, antivirus, network security, or device-management products.

Design, implement, test, and modernize backend services and integrations (TypeScript/Node.js and C++). Lead large projects, write technical specifications and API contracts, enforce coding standards, coach engineers, and drive legacy-to-modern migrations within online banking and core systems.

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.

Develop enterprise and customer-facing media playback solutions within a collaborative development team. Build web and mobile applications using C#, ASP.NET MVC, AngularJS, .NET, JavaScript, Java, Objective-C, Swift, and Python. Implement advanced video security features including forensic watermarking, DRM, and encryption. Collaborate with team members, document technical specifications, communicate with customers, and support project completion.

Build and lead high-performance browser features in modern C++ and Chromium, including tracker blocking, subscription integrations, and responsiveness monitoring. Own complex projects from proposal through post-mortem, solve ambiguous technical problems, make architecture decisions, collaborate asynchronously with product and design, and use metrics to evaluate outcomes in a large-scale consumer codebase.

Build and maintain scalable, cloud-native APIs and high-value core system components using .NET and related technologies. Lead software architecture and testing discussions, enhance core offerings, collaborate cross-functionally, and ensure quality through code reviews, unit testing, functional testing, telemetry, and performance tuning. Mentor teammates and contribute to continuous technical and process improvement.

Leads and develops a software engineering team while contributing hands-on to enterprise application design, coding, testing, code reviews, production support, and technical decisions. Builds scalable solutions using C#, ASP.NET, SQL Server, and modern web technologies; partners with product and business stakeholders; supports Agile delivery, CI/CD, troubleshooting, root cause analysis, and engineering best practices. The role also includes mentoring engineers, monitoring delivery and operational metrics, and driving continuous improvement.

Lead modernization of a 30-year-old Store Management System by reverse engineering EZC file-based platforms, migrating data and applications to PostgreSQL, and developing enterprise C/C++ software. Responsibilities include architecture, systems integration, APIs, ETL, performance optimization, troubleshooting, documentation, and maintaining business continuity. The role also applies AI-assisted development tools for code analysis, documentation, testing, and modernization while mentoring teams and supporting legacy and modern environments.

The C# Developer will design, develop, and support IT solutions using various technologies, ensuring feasibility and leading project initiatives during the software development life cycle.

The Senior Programmer Analyst will develop systems, code and document programs, assist with system design, and improve IT processes and techniques.

The Junior C# Developer will assist in developing system designs, coding, testing, and documenting programs under supervision, while suggesting process improvements.

As a Web Developer, you'll collaborate in a Scrum/Agile team to design and develop web applications using C#, .NET, HTML, and JavaScript, among others.

Design and develop low-latency, high-throughput distributed database kernels for massively parallel analytics. Responsibilities include architecture, modern C++ development, MPI/OpenMP query execution, SIMD and hardware optimization, distributed networking, database internals, in-database machine learning, vector indexing, performance tuning, code reviews, mentoring, and resolving scalability issues across large-scale clustered systems.

Design and develop massively parallel distributed database kernels for real-time analytics at terabyte and petabyte scale. Responsibilities include low-level C++ development, MPP query execution, SIMD and hardware optimization, distributed communication using MPI and RDMA technologies, database internals, vector indexing, in-database machine learning, performance tuning, architecture reviews, mentoring, and resolving scalability issues.

Design and develop low-latency, high-throughput distributed database kernels for massively parallel analytics. Responsibilities include query execution, columnar storage, transaction management, cluster coordination, hardware-aware optimization, SIMD vectorization, RDMA networking, in-database machine learning, vector indexing, performance tuning, architecture reviews, code reviews, mentoring, and resolving scalability issues.

Design and implement complex low latency, high throughput software for financial data distribution, conduct testing, and improve software reliability.

The C# / .NET Developer will design and maintain middleware applications, build Shopify integrations, and support a mobile app backend in a remote work environment.

As a C++ Software Engineer, you will design and develop software solutions, ensuring performance, stability, and quality through testing and collaboration with teams.

Develop user interface components for ArcGIS Pro using C# and WPF, work in an agile team, and design software solutions for raster and imagery processing.

PrivateID seeks a Principal C++ Engineer with at least 10 years of experience to lead complex systems and scale their platform in a remote-first environment.

You will develop and maintain components of the LLVM based toolchain, collaborating with the community while ensuring platform-specific optimizations and tests.

Develop and maintain C/C++ software for telecom environments on Linux. Produce software documentation, use git/Gerrit/GitHub/GitLab, perform shell scripting and basic system administration. OpenStack experience is a plus.

Perform civil/structural engineering and design tasks for power plant upgrades and new projects under senior supervision. Assist with calculations, modifications, equipment walkdowns, and design changes to improve plant performance, safety, and reliability. Work involves field and office duties, travel to client sites, and maintaining unescorted nuclear plant access.