Lightspeed Commerce is the leading POS for restaurants, retail, and golf — Canadian-headquartered, public since 2019. The interview emphasizes POS hardware integration, inventory management, and the unique multi-vertical SaaS challenges.
Process
Recruiter screen → 60-minute coding phone (DSA medium) → onsite virtual: 2 coding, 1 system design, 1 craft deep-dive, 1 behavioral. Cycle: 3–4 weeks.
What they actually ask
- Design a POS that works offline with sync on reconnect — Focus on a local-first store on the device that queues sales while the network is down and reconciles them on reconnect. Interviewers probe idempotency keys, how you resolve conflicting edits when two terminals try to sell the last unit, and how totals stay correct without double-counting.
- Design a multi-location inventory system — Center on keeping stock counts consistent across stores in near real time: reservations when an item enters a cart, transfers between locations, and eventual consistency so a busy store doesn’t oversell. Be ready to weigh a single source of truth against per-location caches.
- Design payment processing with multiple processors — Put an adapter layer in front of each processor so you can route or fail over between them, and lean on idempotency keys and retries so a dropped terminal connection never double-charges. Expect follow-ups on reconciliation and on keeping card data tokenized to shrink PCI scope.
- Coding: medium DSA, often with offline-first or sync framing — Expect arrays, hash maps, and queues, sometimes dressed up as merging offline event logs or deduplicating records after a sync. Write clean, idiomatic code and state your complexity before you optimize.
- Behavioral: customer focus, ownership, working with diverse industry verticals — Come with stories that show you shipped for different verticals (restaurant, retail, golf), owned a feature end to end, and dug into what a specific merchant actually needed. Structure each answer so the situation, your action, and the measurable result are clear.
Levels and comp (2026)
- SE II: CAD$120K–$150K total (Montreal); $135K–$170K (US)
- Senior SE: CAD$150K–$200K / $200K–$260K
- Staff: CAD$210K–$280K / $290K–$380K
- Principal: CAD$300K+ / $400K–$520K
Prep priorities
- Be fluent in PHP (legacy core) or Java (newer services) — Check with your recruiter which language your team uses and practice a medium problem in it; interviewers weigh clean, idiomatic code over framework trivia.
- Understand offline-first sync and conflict resolution — Be ready to walk through how a client queues transactions offline and reconciles on reconnect, including idempotency keys and last-write-wins versus merge strategies that avoid double-charging or overselling.
- Brush up on payment processing and PCI compliance — Know the authorization, capture, and refund flow and why tokenizing card data keeps most systems out of PCI scope, plus how retries stay safe when a terminal drops its connection mid-sale.
Frequently Asked Questions
Is Lightspeed remote-friendly?
Hybrid in Montreal (HQ), Amsterdam, NYC. Some engineering roles remote within Canada/US.
How does Lightspeed compare to Square or Toast?
Square is the dominant SMB POS. Toast specializes in restaurants. Lightspeed competes on multi-vertical SaaS. Comp is comparable; Square pays slightly more.
What is the engineering culture?
Canadian / European tech: collaborative, calm pace, strong work-life balance.
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