Senior Backend Engineer

Piston Technologies, Inc. — On-site, San Francisco Bay Area (Cupertino, CA)

About Piston

Piston Technologies is building a closed-loop payment network for the U.S. trucking industry, changing how fleets pay for and manage fuel. Our flagship product, PistonPay, is a cardless fuel payment platform that gives fleets real-time controls, dynamic underwriting, and full visibility at the pump. We integrate directly with fuel retailers' point-of-sale systems to move high volumes of real-time transactions securely and reliably.

The Role

We're looking for an experienced Backend Engineer to design, build, and own the systems behind fuel payments, fleet transactions, loyalty programs, mobile payments, and fuel retail integrations — work that sits squarely at the intersection of B2B and B2C.

This role is heavily backend-focused and demands strong experience with Node.js, Express.js, PostgreSQL, distributed systems, and XML-based integrations. The ideal candidate is comfortable owning architecture, leading technical initiatives, and delivering highly scalable production systems.

This is a full-time, on-site role in the San Francisco Bay Area.

Responsibilities

• Design, develop, and maintain backend services using Node.js and Express.js
• Architect and support microservice-based applications and RESTful APIs
• Design and optimize PostgreSQL databases for high-volume transactional workloads
• Build and maintain XML-based integrations with third-party platforms and partners
• Develop and support cloud-native applications running in AWS
• Use Docker, Kubernetes, and CI/CD pipelines to deliver reliable production services
• Uphold the security, reliability, and compliance standards expected of a payments platform (e.g., PCI DSS)
• Collaborate with Product, Operations, and Engineering to deliver scalable solutions
• Participate in architectural planning, technical design reviews, and engineering best practices

Required Qualifications

• 5+ years of software engineering experience
• Strong experience with:
  • Node.js
  • Express.js
  • PostgreSQL
  • RESTful API design
  • Microservice architectures
  • Redis
  • XML-based integrations
• Experience designing and operating highly available, transaction-oriented systems
• Experience with AWS
• Experience with Docker, Kubernetes, and CI/CD processes
• Strong understanding of distributed systems, scalability, performance optimization, and database architecture

Preferred Qualifications

Experience with one or more of the following:

• Conexxus standards and XML messaging specifications
• Conexxus Mobile Payments, EPS, or Site Systems implementations
• Verifone Commander and Verifone forecourt integrations
• Gilbarco Passport and forecourt controller integrations
• NACS standards and fuel retail operational workflows
• Fuel payment processing, loyalty platforms, fleet card systems, or forecourt technologies
• Payment authorization, settlement, and reconciliation systems

Ideal Candidate

You're a highly experienced backend engineer who enjoys solving complex integration challenges across B2B and B2C architectures. You have a strong foundation in modern backend development and understand how large-scale transactional systems behave in production. Experience in fuel retail, payments, or convenience retail technology is highly valued.