# Senior Software Engineer – Back End at Tillster > Hybrid · United States · Senior · Backend · open. Source: https://alderhq.app/jobs/ashby%3Atillster%3Ad891d8fb-bf16-4911-8f28-5f2a4dd7db36 (read 2026-11-11). ## Facts (observed) - Company: [Tillster](https://alderhq.app/companies/tillster) - Location text: Los Angeles - Where it can be done from (inferred): Hybrid · United States (evidence: "Location: Los Angeles") - Posted: 2026-07-03 (132 days ago) - First seen by alder: 2026-11-07 · last verified: 2026-11-07 - Reposted: 0 times · edited: 0 times - Apply on the employer's site: https://jobs.ashbyhq.com/Tillster/d891d8fb-bf16-4911-8f28-5f2a4dd7db36 - Skills listed (inferred): Java ## Pay and sponsorship - Posted pay: $150k–$175k per year (from the listing's pay field) - Market band for similar posted roles (Los Angeles, n 19): p25 $178k, median $198k, p75 $199k ## Description (the employer's text) Role: Senior Software Engineer – Back End Hybrid Role, MUST BE BASED IN SAN DIEGO, CA ### About Tillster Tillster, headquartered in the USA, is the global leader in digital ordering and customer engagement solutions. For over a decade we have developed revolutionary self-service, ordering and payments solutions – for mobile, tablet, online, kiosk, call center, and more – creating personalized interactions based on consumer preferences, language, and currency. Our platform is compatible with 15+ unique POS systems, representing over 90% coverage in multi-unit restaurants. We offer one platform; one scalable, enterprise class solution – to create world-class digital engagement solutions. Our mission and passion are one in the same: Empower restaurants and consumers to engage and transact anywhere, anytime, and from any device - one consumer at a time, one order at a time, billions of times over. In doing so, together we are transforming e-commerce in restaurants and make the till grow for Tillster and our customers. ### 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. --- Data: alder (https://alderhq.app). Cite https://alderhq.app/jobs/ashby%3Atillster%3Ad891d8fb-bf16-4911-8f28-5f2a4dd7db36 and the date you read it. Observed facts come from the employer's own listing; location reach, level, family and skills are inferences.