Principal Software Engineer

Principal Engineer, Payments

As a Principal Engineer on the Payments Technology and Engineering team, you'll set technical direction and design best-in-class solutions and do hands-on engineering for products that process millions of B2B payments. The role blends hands-on software development, architecture, coaching, and cross-functional partnership with Product, Architecture, Database, DevOps, Performance Engineering, and Operations — this is not a purely advisory position. You'll bring an AI-first mindset to everything from daily coding to system design, treating agentic AI tooling as a default part of the SDLC rather than an occasional aid. This is a senior individual-contributor role — you'll drive impact through system design, architecture, mentorship, and cross-team influence.

What You'll Do:

Technical Leadership & Architecture

Define and drive the Payments platform's technical approach, system design decisions, and engineering best practices.

Advance platform scalability, reliability, and observability through API-first and event-driven design, distributed systems, cloud-native architecture, and fault-tolerant patterns (e.g., circuit breakers, retries with backoff, etc.).

Partner with Solution and Enterprise Architects, and with developers, to determine optimal designs for architecture, efficiency, maintainability, and scalability across new and existing capabilities.

Collaborate with Product, Business Operations, and Engineering leaders to align technical solutions with business needs and shape engineering roadmaps.

AI-First Engineering

Adopt an agentic AI-based SDLC as the default approach to building software — using AI coding agents to scaffold, implement, test, and review code, not just as an occasional assist.

Work fluently with AI harness / coding-agent tools (e.g., Cursor, Claude Code, VS Code with GitHub Copilot) as part of your daily workflow and help establish team-wide standards and best practices for their use.

Champion AI-driven engineering practices — intelligent automation, predictive analytics, and self-healing systems — to improve development efficiency and system resilience.

Identify and implement AI-based solutions for Payments product initiatives, from proof of concept through production.

Model and promote an AI-first mindset across the team — evaluating new AI tooling, sharing what works, and pushing the team toward higher leverage.

Quality, Security & Delivery

Solve problems, debug, and optimize code for performance and security, with attention to the compliance and regulatory standards that apply to payment processing (e.g., PCI-DSS).

Own code quality and unit test coverage; partner with QA to design and review test cases so the platform meets customer expectations.

Perform code reviews and approve pull requests, ensuring code follows documented standards and best practices.

Own the health of the software delivery pipeline and guide the team in improving it.

Hands-On Development, Mentorship & Collaboration

Stay hands-on — writing code, building proofs of concept, and pairing directly with engineers — while also setting architectural direction; this role is a blend of building and leading, not one or the other.

Mentor and coach developers, with particular focus on senior engineers, through code review, design discussions, and technical guidance.

Partner closely with Product and Operations to ensure technical solutions align with business needs and day-to-day operational realities.

Influence engineering culture and product solutions — within the team and company-wide — through thought leadership.

Drive full lifecycle application development: research technical options for new features, provide guidance based on findings, and build proofs of concept to validate the best approach.

What We're Looking For:

Required

Demonstrated agentic AI-first approach to the SDLC, with hands-on fluency in AI coding-agent tools such as Cursor, Claude Code, or VS Code with GitHub Copilot.

Knowledge and experience in AI agent development using tools and frameworks such as LangChain/LangGraph, Databricks, vector databases, and open- and closed-weight LLMs.

Broad AI-first mindset — comfortable evaluating and adopting new AI tooling and practices and coaching other engineers to do the same.

Bachelor's or master's degree in computer science, Computer Engineering, or a related field — or equivalent practical experience — plus 10+ years of .NET software development experience building web-based applications.

Strong knowledge of the Microsoft development stack: .NET Core, C#, JavaScript, RESTful services, ORM, T-SQL, JSON, MVC, XML, HTML, and CSS.

Strong design and architecture mindset, with experience designing scalable, high-performance, secure enterprise applications in Azure (or another public cloud).

Proficiency in modern engineering practices: unit testing, CI/CD pipelines, DevOps, microservices, and containerization (Docker/Kubernetes).

Deep knowledge of sound coding practices — unit testing, object-oriented design, and design patterns.

Comprehensive knowledge of databases (RDBMS and NoSQL) and advanced SQL, including stored procedures, indexes, functions, and triggers.

Experience with event-driven and messaging architectures (e.g., Kafka, Azure Service Bus, or Event Grid).

Thorough knowledge of source control (Git) in continuous integration environments.

Hands-on experience with Agile processes (Scrum/Kanban).

Experience with observability/monitoring tooling (e.g., Datadog, Application Insights, OpenTelemetry).

Strong written and verbal communication skills, with a demonstrated ability to influence technical direction across teams and communicate with non-technical stakeholders.

Preferred

Experience in payments, fintech, or financial services, including familiarity with compliance frameworks such as PCI-DSS.

Prior experience mentoring senior engineers or acting as a technical lead without formal management authority.

About AvidXchange

AvidXchange is a leading provider of accounts payable (“AP”) automation software and payment solutions for middle-market businesses and their suppliers. By trade, we are a technology company, but if you ask anyone who works here, they’ll tell you our people are at the core of who we are. At AvidXchange, mindset is everything . We are Connected as People , Growth Minded , and Customer Obsessed . These three mindsets represent our culture – who we are, who we’ve always been, and they guide us to improve every day. Since our founding in 2000 in Charlotte, NC, we’ve created a company of over 1,500 teammates working across the U.S., or remotely. AvidXchange is proud to be Certified™ as a Great Place to Work ®. The prestigious recognition is based on anonymous data from our teammates and makes official what our teammates have known for years – that AvidXchange is a Great Place to Work®.

Who you are:

A go-getter with an entrepreneurial mindset – that means you are not afraid of taking risks, winning big or facing the unknown.

Someone who understands that business is people centric. Connecting with others as humans first allows you to develop mutually beneficial working relationships.

Focused on making a difference for our customers. AvidXchange exists to help solve complex problems for our customers so we can all realize our potential.

What you’ll get:

AvidXchange teammates (we call them AvidXers) get the perks and prestige of a growing tech company paired with the flexibility of a founder-led startup. We help our AvidXers develop as professionals and as human beings, providing work/life balance, development programs, and competitive benefits. At AvidXchange, we are building more than a tech company – we are building an experience. We remain committed to a culture where you can fully be 'you’ – connected with others, chasing big goals, and making a meaningful impact. If you want to