Senior Software Engineer (Card Present)

We are expanding our Card Present platform, the infrastructure that powers in-person, tap, dip, and swipe transactions at point-of-sale, and are looking for a Senior Engineer who combines deep payments domain expertise with strong backend engineering fundamentals.

Responsibilities

• Design, develop, and maintain backend services that manage communication between payment terminals and our processing infrastructure, supporting EMV chip, NFC/contactless, and magnetic stripe transaction flows.
• Integrate with device management platforms and terminal SDKs including solutions such as Clover, Stripe Terminal, Square, and similar off-the-shelf card present providers, adapting their APIs to fit our platform architecture.
• Implement and maintain device hub capabilities including terminal provisioning, configuration management, firmware coordination, and health monitoring.
• Own and drive EMV Level 3 certification efforts in partnership with payment networks and device vendors, coordinating test plans, managing certification tooling, and resolving certification findings.
• Design and build card-present infrastructure with international markets in mind, accounting for regional EMV implementation differences, multi-currency support, and varying certification requirements across acquiring markets.
• Build scalable, maintainable backend services using .NET and C#, adhering to established architectural patterns and contributing to their evolution.

• Implement robust retry logic, timeout handling, and graceful degradation to ensure transaction integrity even in the presence of network instability or device failures.

• Write secure code that meets PCI DSS requirements across all card-present transaction flows, with a particular focus on cardholder data handling, encryption, and key management.
• Apply point-to-point encryption (P2PE) and tokenization standards correctly within device integration and transaction processing layers.

• Act as a technical resource and mentor for junior and mid-level engineers on the squad, supporting their growth through pair programming, code review feedback, and knowledge sharing.
• Document card-present domain knowledge including certification processes, integration quirks, device-specific behaviors

 Qualifications

• Strong proficiency in C# and the .NET ecosystem, with experience building production-grade backend services and APIs.
• Hands-on experience with EMV payment flows including chip, contactless/NFC, and magnetic stripe, ideally including direct involvement in EMV Level 3 certification processes.
• Experience integrating with payment terminal hardware and device management platforms, with an understanding of terminal communication protocols (TLV, ISO 8583, or similar).
• Solid understanding of PCI DSS requirements as they apply to card-present environments, including encryption, key injection, and secure cardholder data handling.
• Experience designing and building RESTful APIs with a focus on clarity, versioning, and reliability.
• Proven ability to build low-latency, high-reliability backend services in a payments or similarly demanding production environment.
• Direct experience with Clover, Stripe Terminal, Square, or similar off-the-shelf card present platforms and their developer SDKs.
• Familiarity with EMV kernel development/ customization, regional EMV certification requirements and acquiring bank differences across international markets.
• Background working with Ingenico, Verifone, PAX, or other terminal hardware vendors.
• Experience with network tokenization or scheme token management in a card-present context.

Job Type: Full-time

The Company is committed to compliance with all applicable laws providing equal employment opportunities. This commitment applies to all persons involved in Company operations. The Company prohibits unlawful discrimination against any job applicant, employee, or unpaid intern by any employee of the Company, including supervisors and coworkers. Pay discrimination between employees of the opposite sex or between employees of another race or ethnicity performing substantially similar work, as defined by the California Fair Pay Act and federal law, is prohibited.