Tillster

Senior Software Engineer – Back End

Tillster
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22 days ago
San Diego, CA, USASenior

Base Salary

$150k - $165k/yr

Responsibilities

  • Own the kiosk payment domain, including authorization, capture, void, refund, reversal, settlement, and reconciliation.
  • Re-architect the payment platform into a modular, pluggable, versioned SDK over the PayTerminal SPI.
  • Design a unified terminal abstraction covering integrated, semi-integrated, cloud, REST-based, and cash-processing devices.
  • Build integration testing, simulation, certification, and regression-testing infrastructure for new and external integrations.
  • Define patterns for idempotency, transaction recovery, timeouts, health monitoring, concurrency, and reconciliation.
  • Implement payment-terminal integrations from byte-level protocols through the high-level PayTerminal API.
  • Develop and maintain serial and USB transport integrations, including reconnection and event-driven reads.
  • Integrate processor APIs and terminal SDKs with retry, polling, webhook, and reconciliation workflows.
  • Design PCI-DSS scope minimization using tokenization, P2PE, TLS/mTLS, and certificate and key handling.
  • Lead architecture and design reviews, establish technical direction, and mentor engineers.

Requirements

  • 6+ years of backend engineering experience with strong Java, OOP, and distributed-systems design skills.
  • Experience with multi-module Maven/Java applications using Spring.
  • Demonstrated experience designing extensible plugin or SPI-based architectures, such as ServiceLoader, OSGi, Spring plugin models, or public SDKs.
  • Hands-on experience with serial or USB communication and binary protocols, including TLV, BCD, bitmaps, length-prefixed fields, and state machines.
  • Direct payment-terminal or POS integration experience with providers such as Verifone, Ingenico, Adyen, Shift4, FreedomPay, SIX, Nepting, SiTef, or Redsys.
  • Understanding of card transaction lifecycles, PCI-DSS boundaries, tokenization, and TLS/mTLS in production.
  • Track record of technical leadership, design ownership, standards-setting, and mentoring.
  • Experience with EMV, ISO 8583, ZVT, or OPI is a strong plus.
  • Experience with cash automation, regional acquiring, multi-currency payments, loyalty, stored value, wallets, vendor certification, 3-D Secure, SCA, or fraud and risk tooling is preferred.

Benefits

  • Hybrid role requiring the employee to be based in San Diego, California; local candidates only.
  • Medical, dental, vision, FSA, healthcare and dependent-care reimbursement programs, an Employee Assistance Program, and Optum Care counseling services are available to eligible full-time employees and dependents.
  • Ten paid holidays per calendar year.
  • Full-time employees receive 15 days of PTO during the first 12 months and 22 days in subsequent years; eligible part-time employees receive prorated PTO.
  • 401(k) plan eligibility begins on the employment start date.
  • College tuition and education assistance, Udemy courses, and ongoing learning and development opportunities are available.

Tech Stack

JavaMaven

Categories

Tillster

About Tillster

201-500 employees
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