Senior Software Engineer – Back End Location San Diego Office Employment Type Full time Location Type Hybrid Department Software Engineering Compensation - $150K – $180K Role: Senior Software Engineer – Back End Hybrid Role, MUST BE BASED IN SAN DIEGO, CA About the Role We are looking for a Senior Engineer (bordering on Architect) to own and evolve the payment-terminal platform behind our kiosks: a layer of 40+ integrations spanning card-present terminals, semi-integrated and cloud processors, and cash automation. You will re-architect this into a modular, pluggable SDK so internal teams and external/third-party developers can build new integrations against a stable, versioned contract without forking the core, and you will stay hands-on, implementing new integrations down to the wire-level protocol. What You'll Do (architecture and ownership) - Own the payments domain end to end on the kiosk platform: authorize, capture, void, refund, reversal, settlement (EOD), and reconciliation. - Re-architect the platform into a pluggable payment SDK: design the plugin contract and lifecycle (discovery/registration, versioning and backward compatibility, capability negotiation, dependency isolation, per-integration configuration and secrets) on top of the existing PayTerminal SPI. - Design a terminal abstraction that cleanly spans integrated vs. semi-integrated vs. cloud/REST processors and cash devices, so callers code to one model regardless of transport or vendor. - Build the integration test and certification harness (extending the current mock-terminal approach) so a new or external integration can be validated, simulated, and regression-tested before it touches real hardware. - Set platform-wide patterns for correctness in money movement: idempotency, transaction recovery and reversal, timeouts, heartbeat/health, concurrency, and reconciliation, in a system where double-charges and dropped captures are unacceptable. - Design for PCI-DSS scope minimization: tokenization, P2PE, per-processor TLS/mTLS and certificate/key handling, so cardholder data stays out of in-scope services. Partner with security/QSA on audits. - Drive architecture and design reviews, set technical direction for the integration layer, and mentor engineers building integrations. What You'll Do (hands-on, low to high level) - Implement new terminal integrations end to end, from byte-level protocol (framing, TLV/BMP/APDU, BCD/LLVAR, checksums, ACK/NAK state machines) up to the high-level PayTerminal API. - Work directly with serial (RS-232 / USB-serial via jssc) and USB (usb4java) transports: port handling, event-driven reads, reconnection, and timing. - Integrate high-level and cloud processor APIs (REST/SOAP, webhooks, semi-integrated terminal SDKs) with robust retry, polling, and reconciliation. - Debug live hardware: protocol traces, terminal logs, packet captures, and vendor certification cycles. About You (required) - 6+ years back-end engineering with strong Java (the platform is multi-module Maven/Java on Spring) and solid OOP and distributed-systems design. - Demonstrated experience designing extensible / plugin / SPI-based architectures (ServiceLoader, OSGi, Spring plugin models, or public SDKs consumed by other teams or third parties). - Hands-on low-level device and protocol experience: serial and/or USB communication and binary protocol implementation (TLV, BCD, bitmaps, length-prefixed fields, state machines). EMV, ISO 8583, ZVT, or OPI a strong plus. - Direct payment-terminal / POS integration experience (Verifone, Ingenico, Adyen, Shift4, FreedomPay, SIX, Nepting, SiTef, Redsys, Worldpay, or comparable), and a clear understanding of integrated vs. semi-integrated models. - Solid grasp of the card transaction lifecycle (auth, capture, void, refund, settlement, reversal) and PCI-DSS boundaries, tokenization, and TLS/mTLS in production. - Track record of technical leadership: leading designs, setting standards, and mentoring engineers. Nice-to-haves - Cash automation and recyclers (Vynamic Cash or similar), end-of-day and reconciliation tooling. - Regional acquiring experience (LatAm, EU, Middle East) and multi-currency payments. - Loyalty, stored-value, gift, or wallet (Apple Pay / Google Pay) integration. - Vendor certification experience with acquirers and processors; 3-D Secure / SCA, fraud/risk tooling. Thriving at Tillster As a member of Tillster, you will embody our core values: · Put Customers First: Prioritize the needs and satisfaction of our customers in all decisions and actions appropriate to Tillster’s stage of development, resources, and stated goals. · Collaborate: Work together effectively, leveraging diverse perspectives to achieve common goals. · Innovate: Embrace creativity and pursue new ideas to drive progress and improvement. · Operate from Data: Use strong critical thinking skills to make informed decisions based on accurate and relevant data. · Drive Results: Focus on achieving tangible outcomes and delivering high performance. · Own It: Take responsibility for your actions and the success of your work. · Be Passionate and Have Fun: Bring enthusiasm to your work and enjoy the journey. Pay and Benefits (USA) - Salary is $150,000 - $185,000 DOE - Health Benefits: All full-time, regular employees and their dependents are eligible for medical, dental, vision and FSA benefits. Additional health benefits include Healthcare and Dependent Care reimbursement programs, Employee Assistance Program (“EAP”) and Optum Care 24-hour confidential medical counseling services. - Holidays: The company observes ten (10) paid holidays per calendar year. - Paid Time Off (PTO): Full-time, regular employees earn 15 days of PTO in the first 12-months of continuous service, and 22 days in subsequent years. Eligible part-time employees earn pro-rated PTO. - Retirement: Effective with your employment start date, you will be eligible to participate in the 401(k) Plan. - Education, Learning & Development: We offer college tuition and education assistance programs; Udemy Learning courses; and ongoing learning and development opportunities.

Role Description We are seeking a problem-solving QA Automation/Software Development Engineer in Test (SDET) to join the tech team, with a primary focus on payroll integrations. This agile role revolves around improving software quality through coding. The engineer will be responsible for: - Testing integrations with external third parties - Building comprehensive integration tests - Developing mock services for APIs Collaboration is key, as this role works closely with the tech lead and product managers to define acceptance criteria and implement new test scenarios within a Docker and Jenkins-based QA infrastructure. Qualifications - 5+ years of software testing experience in an automated environment - Strong coding experience in Python (Strict core requirement) - Proven experience testing APIs and building integration tests with external/third-party systems - Hands-on experience building and maintaining mock services for APIs - Ability to write automated tests directly from acceptance criteria - Understanding of build automation, application deployment, and CI pipelines (Docker, Jenkins) - Experience with SQL databases and advanced RESTful APIs Requirements - Strong problem-solving abilities and a passion for learning new things - Enthusiasm for driving product quality through test automation Benefits - Monetary compensation - Year-end Bonus - IMSS, AFORE, INFONAVIT - Major Medical Expenses Insurance - Life Insurance - Funeral Expenses Coverage - TDU Membership - MediAccess - Health Check-Up Subsidy - Preferential rates for car insurance - Vacations - Official Mexican Holidays - Life Happens Days - Bereavement Leave - Civil Marriage Leave - English Classes - Certifications - Educational Agreements (Talisis, U-ERRE, UNID, TecMilenio, Tec de Monterrey, UDEM, SPIS) - Corporate Agreements & Discounts (Sorteos Tec, Envia Flores, TopGolf) - Taquitos Rewards - Birthday Bonus - Work-from-home Bonus - Laptop Policy

• Own the technical onboarding experience for new customers • Lead hands-on enablement sessions to implement across test frameworks and CI/CD pipelines • Guide customers through initial use cases that align with their success criteria • Ensure customers reach meaningful value quickly and confidently • Drive sustained adoption across teams, projects, and workflows • Help customers expand test coverage, standardize best practices, and scale usage over time • Provide expert guidance on test automation strategy, visual testing, and quality maturity • Identify adoption gaps and proactively recommend technical improvements • Serve as the primary technical point of contact for assigned accounts • Troubleshoot and resolve complex technical challenges in coordination with Support team • Conduct technical health checks, architecture reviews, and optimization sessions • Lead root cause analysis for escalations and recurring issues • Proactively identify technical risks that could impact adoption, satisfaction, or renewal • Partner with CSMs to support renewals and expansions with strong technical validation • Advocate for customer needs by sharing product feedback, patterns, and gaps with Product and Engineering • Collaborate closely with Product, Engineering, Support, Sales, and Customer Success • Contribute to onboarding playbooks, best practices, and enablement materials • Help improve internal processes that scale technical customer success

Role Description Participate in the entire product testing process, including: - Requirements analysis - Test case design - Execution - Defect tracking Core Testing Tasks: - Perform functional testing, regression testing, and API testing to ensure product quality. Environment & Data Management: - Build and maintain testing environments - Manage test data - Submit and track bugs - Assist developers in locating and reproducing issues Process Optimization: - Familiarize yourself with R&D testing workflows - Learn and master the company’s business logic and internal testing protocols Qualifications - Proficient in at least one programming language (Python, Java, Go, or C++); capable of writing basic scripts and performing API testing. - Fluent in Mandarin & English - Solid understanding of R&D testing workflows and software testing theory (e.g., test design methodology, boundary value analysis, etc.). - Keen insight into system design and implementation; ability to provide constructive suggestions for product optimization and user experience. Requirements - Background in Finance or a strong interest in Web3 and Blockchain technologies. - Experience with automation and testing tools such as Selenium, Pytest, or Postman. Benefits - Study Growth Fund: We support your professional development and continuous learning. - Internal Events: Participate in regular team-building activities, workshops, and events designed to promote collaboration and innovation. - Global Collaboration: Be part of a diverse, international team, working alongside colleagues from around the world. - Career Advancement: Access opportunities for growth and advancement within a rapidly expanding global company. - Internal Mobility: Grow with us - Your long-term development is important to us. We offer internal job opportunities to help build your career path.