Senior Software Engineer (C/C++)

LaunchCode; St. Louis (MO); Hybrid; USD 110,000 - 150,000; Part time

Job summary

LaunchCode is partnering with a company in O'Fallon, MO to hire a Senior Software Engineer (C/C++) on a contract-to-hire basis. The role focuses on designing and delivering high-performance, scalable payment processing systems in an Agile environment.

The position requires three days onsite weekly and involves development, testing, and production support across the full software lifecycle. Strong C/C++, testing, and Linux skills are essential.

Qualifications

• Proven experience with C/C++ in high-performance, scalable systems.
• Experience in functional, integration, system, and UAT testing.
• Knowledge of Linux/Unix and shell scripting for automation.
• Ability to design test strategies from requirements and designs.

Responsibilities

• Design, develop, and maintain C/C++ software for high-performance systems.
• Create and execute unit tests and automated testing solutions.
• Develop test plans from requirements and designs and perform various testing types.
• Analyze logs and system behavior; perform root-cause analysis on defects.
• Contribute to code reviews and engineering best practices.
• Collaborate with cross-functional teams and support production systems.

Skills

C/C++

Java experience

Testing

Linux/Unix

Shell scripting

Git

Algorithms & data structures

Agile / CI/CD

Debugging

Production support

Education

Bachelor's degree in Computer Science / Software Engineering / IT / Mathematics or equivalent

Tools

Google Test

Job description

Brief Description

Location: O'Fallon, MO (Hybrid – 3 days onsite per week/depending on project needs)

Position Type: Contract-to-Hire (6–12 months before potential conversion)

Company: The name of our partner organization will be disclosed to candidates selected to move forward in the interview process. This is an opportunity through LaunchCode, working with one of our company partners.

Overview

Our company partner's Global Credit Authorization team is seeking a Senior Software Engineer (C/C++) to build and enhance high-performance, mission-critical systems that power secure, reliable payment processing at global scale.

In this role, you will leverage strong software engineering expertise to design, develop, test, and support resilient and scalable applications. You will contribute across the software development lifecycle, working closely with engineers, architects, and product stakeholders to deliver high-quality solutions that meet demanding performance and reliability requirements.

You'll work in a collaborative, fast-paced Agile environment where quality, reliability, automation, and continuous improvement are core to how software is developed.

This is a hybrid position based in O'Fallon, MO, requiring three days per week onsite.

Role Responsibilities

• Design, develop, and maintain software solutions using C/C++ for high-performance, scalable systems.
• Develop robust unit tests using Google Test and contribute to automated testing solutions.
• Create and execute test plans based on functional requirements and technical designs.
• Perform functional, integration, system, and User Acceptance Testing (UAT) activities.
• Analyze logs, traces, and system behavior to validate functionality and ensure adequate test coverage.
• Troubleshoot software defects, perform root cause analysis, and implement effective solutions.
• Contribute to software quality, reliability, and production readiness throughout the development lifecycle.
• Identify opportunities to improve application performance, automation, and engineering efficiency.
• Prepare technical designs, implementation plans, and supporting documentation.
• Participate in requirements analysis, backlog refinement, sprint planning, and Agile ceremonies.
• Collaborate with engineers, architects, product owners, and cross-functional teams to deliver business outcomes.
• Support production systems through troubleshooting, incident response, and on-call participation.
• Contribute to code reviews and technical discussions to promote engineering best practices.
• Share technical knowledge and support the growth of fellow team members.
• Communicate technical concepts and project status effectively with technical and non-technical stakeholders.

Qualifications

• Strong software development experience using C/C++ (Java experience is also valued).
• Experience developing and executing functional, integration, system, and UAT testing.
• Experience creating test strategies and test plans from technical requirements and design documentation.
• Solid understanding of software quality practices, test automation, defect management, and test coverage analysis.
• Strong knowledge of Linux/Unix environments and command-line tools.
• Proficiency with scripting languages, preferably Shell scripting.
• Experience using source control systems such as Git in a collaborative development environment.
• Strong understanding of algorithms, data structures, operating systems, networking fundamentals, and distributed systems concepts.
• Experience developing applications for highly available, performance-sensitive systems.
• Familiarity with Agile methodologies, including Scrum, Kanban, CI/CD, and iterative software delivery practices.
• Strong problem-solving, analytical, debugging, and troubleshooting skills.
• Ability to manage multiple priorities and deliver quality results in a fast-paced environment.
• Effective verbal and written communication skills with the ability to collaborate across teams.
• Demonstrated ability to work independently while contributing to a highly collaborative engineering culture.
• Bachelor's degree in Computer Science, Software Engineering, Information Technology, Mathematics, or a related field, or equivalent practical experience.