Senior Software Developer

Pro Search is partnering with a confidential Information Technology client to hire a Senior Software Developer for the Portland, Maine location. This position blends hands‑on software development with technical leadership responsibilities. It is an ideal opportunity for a developer who is comfortable guiding a small team while contributing directly to the architecture and performance of mission‑critical systems. The environment supports high‑volume processing and demands exceptional reliability, security, and speed.

Its systems use a highly segmented architecture to ensure strong security, dependable uptime, and efficient performance across a diverse client base. Every component is designed with redundancy, compliance, and scalability in mind.

• Lead and mentor a development team of three to four developers while remaining actively involved in development work
• Design and maintain public facing web applications and API endpoints for payment processing
• Architect backend services and database schemas that support high volume and high availability environments
• Ensure the reliability of credit card and ACH processing systems that operate continuously
• Maintain PCI Level 1 compliance across applications, infrastructure and processes
• Conduct security reviews and penetration testing while applying OWASP Top 10 best practices
• Monitor and optimize performance for large‑scale transaction processing
• Manage redundancy and high availability strategies for critical services
• Balance hands‑on software development with team leadership and project coordination

• Strong proficiency in ASP.NET Core, Microsoft .NET Framework and Microsoft .NET Core
• Experience working with Windows Communication Foundation and Windows Services
• Expertise in designing and implementing REST APIs
• Working knowledge of HTML, CSS and curl
• Advanced SQL Server experience including Availability Groups and high‑availability configurations
• Experience with database redundancy and disaster recovery strategies

• Demonstrated experience supporting PCI Level 1 requirements
• Strong understanding of payment industry security practices
• Hands‑on experience with security assessments and penetration testing
• Familiarity with OWASP Top 10 vulnerabilities and mitigation techniques

• Proven success leading small to mid‑sized development teams
• Ability to balance team management with active development responsibilities
• Strength in problem solving, prioritization and technical decision making
• Excellent communication skills for both technical and non‑technical audiences

• Experience working in payment processing or financial services
• Familiarity with high‑volume transaction processing environments
• Experience with continuous monitoring and alerting systems
• Background with segmented or microservices architectures
• Experience participating in PCI DSS audits
• Fast‑paced environment supporting mission‑critical financial systems
• On‑call responsibilities for monitoring and incident response
• Highly collaborative culture built around security, reliability, and continuous improvement
• Opportunity to work with modern technologies while supporting legacy code where needed

This position gives you the opportunity to work on systems that have a direct impact on thousands of daily transactions. You will play a key role in strengthening a secure and high‑performing platform while guiding a team of developers who value excellence and collaboration. This is a place where technical leadership and hands‑on development are equally important and where your contributions help support clients who rely on nonstop payment processing.

If you are an experienced Senior Software Developer who thrives in high‑responsibility environments and enjoys leading development efforts while building secure and scalable systems, we encourage you to apply through Pro Search. This is your opportunity to shape the future of a mission‑critical payment processing platform in Portland ME.

• Mid‑Senior level

• Full‑time

• Information Technology

• Medical insurance
• 401(k)