Senior Software Engineer

Who We Are

Finance leaders choose Billtrust to get paid faster, control costs, and maximize customer satisfaction. As the leader in B2B accounts receivable workflow and payment software, we provide the world’s leading brands with AI-powered solutions across the full AR lifecycle—from invoice presentment and payment processing to cash application and collections. With over 2,600 global customers, more than $1 trillion in invoice dollars processed, and a proprietary network of 13 million buyers, Billtrust delivers business value through deep industry expertise and a culture relentlessly focused on meaningful customer outcomes.

We’re an AI-first company, not just in what we build for our customers, but in how we work. Across every function, our teams use AI tools daily to work faster, make better decisions, and deliver higher-quality outcomes. We hire exceptional people, give them cutting-edge AI capabilities, and measure success by the impact they create. If you want to do the best work of your career at the frontier of AI and fintech, Billtrust is the place to do it.

Our Values

Customers

We relentlessly increase value for customer and do the right thing for them.

Action

We make ‘thoughtfully fast’ decisions, act quickly, cut through red tape, deliver progress not perfection, take ownership and accountability.

Team Spirit

We put the team ahead of ourselves, foster trust and respect, collaborate with passion, despise toxic politics, value our differences, and celebrate together.

Innovation

We challenge the status quo, experiment thoughtfully, and are novel and brilliant in what we create.

Excellence

We love to win, but we hate losing even more. We aspire to be the best and take pride in our work. When we fall short, we own it and come back stronger.

Senior Software Engineer, PHP

The Software Engineer designs solutions and delivers backend features for our product platform using AI tools throughout the development lifecycle. As part of a small collaborative pod, this position is accountable for features end-to-end—leveraging AI assistance for specification, implementation, quality validation, deployment, and post-deployment support while ensuring quality outcomes at each stage. This is primarily a backend role focused on high-throughput data ingestion, PDF processing, and working with large datasets. The Software Engineer interfaces with Technical PMs and fellow engineers to deliver scalable, performant services with high velocity. This position also helps evolve our Al-assisted development practices and mentors Associate Engineers on effective AI tool usage.

What You’ll Do

Job Summary

We are seeking a skilled Software Engineer (PHP) to design and deliver scalable web application features in a collaborative, high‑velocity environment. You will work end‑to‑end across the development lifecycle—leveraging AI tools for specification, implementation, testing, deployment, and support—while ensuring quality outcomes. This role involves close collaboration with Technical PMs and engineers, mentoring junior team members, and contributing to the evolution of AI‑assisted development practices.

Key Responsibilities

• Translate product requirements into detailed technical specifications with clear acceptance criteria.
• Design, build, and maintain secure, performant web application features using PHP.
• Implement and optimize REST APIs following established patterns.
• Review AI‑generated and peer code for correctness, security, and architectural alignment.
• Validate AI‑generated tests and ensure comprehensive coverage.
• Optimize queries, schemas, and storage strategies across MySQL and NoSQL (MongoDB/DynamoDB) databases.
• Deploy and maintain applications on AWS with a DevOps mindset.
• Mentor Associate Engineers on effective AI tool usage and specification techniques.
• Contribute to evolving AI‑assisted development practices, including spec templates and validation workflows.
• Own domain knowledge within your pod and support ongoing application maintenance.

Qualifications

Required

• Bachelor’s degree in Computer Science or equivalent experience.
• 3+ years of experience designing and implementing scalable web applications.
• Strong production coding skills in PHP.
• Expertise in MySQL (schema design, query optimization).
• Knowledge of NoSQL databases (MongoDB/DynamoDB).
• Experience designing and implementing REST APIs.
• Hands‑on experience with AWS deployment.
• Proficiency in Git or similar source control tools.
• Experience working with AI coding assistants (Claude Code, Windsurf, etc.).
• Strong collaboration, communication, and code review skills.

Preferred

• Experience with spec‑driven AI workflows.
• Exposure to .NET (C#) or Python.
• Familiarity with Kafka/message queues.
• Experience mentoring junior engineers.
• Understanding of testable application design principles.
• Contributions to process improvements in development practices.