Senior Software Developer

ProSearch; Portland (ME); On-site; USD 90,000 - 130,000; Full time

Job summary

A technology recruitment agency is searching for a Senior Software Developer in Portland, Maine, to blend hands-on software development with leadership responsibilities. The ideal candidate will guide a small team while designing applications that support high volume payment processing. Responsibilities include ensuring PCI compliance and conducting security assessments, in a collaborative environment focused on security and reliability. Candidates should have strong expertise in ASP.NET Core and experience with REST APIs. This role is critical in supporting daily transactions for clients.

Qualifications

• Strong proficiency in ASP.NET Core and Microsoft .NET Framework.
• Experience with REST APIs and SQL Server, including Availability Groups.
• Hands-on experience with penetration testing and security assessments.

Responsibilities

• Lead and mentor a small development team while actively coding.
• Design and maintain web applications and payment processing APIs.
• Ensure PCI Level 1 compliance and optimize performance.

Skills

ASP.NET Core

Microsoft .NET Framework

REST APIs

SQL Server

HTML

CSS

Windows Communication Foundation

Windows Services

Penetration testing

Job description

Overview

ProSearch 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.

Key Responsibilities

• 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

Required Qualifications

Technical Expertise

• 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

Security and Compliance

• 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

Leadership and Management

• 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

Preferred Qualifications

• 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

Why Join Us

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.

Ready to Apply

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 ProSearch. This is your opportunity to shape the future of a mission critical payment processing platform in Portland ME.