Tillster

Senior Software Engineer – Back End

Tillster
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2 months ago

Base Salary

$150k - $175k/yr

Responsibilities

  • Own the kiosk payment domain end to end, including authorization, capture, void, refund, reversal, settlement, and reconciliation.
  • Re-architect the existing PayTerminal SPI into a modular, pluggable, versioned SDK with plugin discovery, lifecycle management, capability negotiation, dependency isolation, configuration, and secrets handling.
  • Design a unified terminal abstraction across integrated, semi-integrated, cloud/REST processors, and cash devices.
  • Build integration testing, simulation, certification, and regression-testing harnesses for new and external integrations.
  • Establish platform-wide patterns for idempotency, transaction recovery, reversals, timeouts, health monitoring, concurrency, and reconciliation.
  • Design PCI-DSS scope minimization using tokenization, P2PE, TLS/mTLS, and certificate and key handling, partnering with security and QSA teams on audits.
  • Implement terminal integrations from byte-level protocols through the high-level PayTerminal API.
  • Work with RS-232, USB-serial, USB, device reconnection, event-driven reads, and timing; integrate REST/SOAP APIs, webhooks, polling, retries, and reconciliation.
  • Debug live hardware using protocol traces, terminal logs, packet captures, and vendor certification cycles.
  • Drive architecture and design reviews, set technical direction, and mentor engineers building integrations.

Requirements

  • 6+ years of backend engineering experience with strong Java, object-oriented programming, and distributed-systems design skills.
  • Experience designing extensible plugin, SPI-based, or public SDK architectures, such as ServiceLoader, OSGi, Spring plugin models, or SDKs used by other teams or third parties.
  • Hands-on serial or USB communication experience and binary protocol implementation involving 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, Redsys, Worldpay, or comparable platforms.
  • Understanding of card transaction lifecycles, PCI-DSS boundaries, tokenization, and production TLS/mTLS.
  • Demonstrated technical leadership through design leadership, standards-setting, and engineering mentorship.
  • Experience with EMV, ISO 8583, ZVT, or OPI is a strong plus.
  • Experience with cash automation and recyclers, regional acquiring, multi-currency payments, loyalty, stored value, gift, wallet integrations, 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.
  • Full-time regular employees and dependents are eligible for medical, dental, vision, FSA, healthcare and dependent-care reimbursement programs, EAP, and Optum Care counseling services.
  • 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.
  • Eligibility to participate in the 401(k) plan begins with employment.
  • College tuition and education assistance, Udemy courses, and ongoing learning and development opportunities.

Tech Stack

JavaMavenSOAP

Categories

Tillster

About Tillster

201-500 employees
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