Senior Software Engineer, Full Stack

Trusted by more than 18,000 Shopify and Shopify Plus stores—like Brooklinen, Ruggable, True Classic and Dr. Squatch—Postscript gives ecommerce brands the tools they need to run a world-class SMS marketing program. We’re on a mission to make SMS the number-one revenue channel for ecommerce merchants by delivering an easy-to-use platform where they can grow their subscriber list, develop and test their messaging strategy, deliver excellent customer service, and drive sales and loyalty—all in one place. We believe SMS is the most important marketing and sales channel of the decade, and that vision drives everything we do. Postscript was founded in 2018 as a 100% remote organization. With more than 250 employees (and counting!), we’re backed by Greylock, Y Combinator, and other top investors. As a Senior Backend Engineer on the App Systems team, you'll be a high-ownership contributor to Fondue — Postscript's cashback, discounting, and incentives product — as well as broader offers and incentives infrastructure across the platform. App Systems owns some of Postscript's most critical systems: billing, entitlements, onboarding, and core merchant data. This role sits at the center of high-margin revenue and a product with a competitive, high-visibility roadmap. You'll be working on evolving, distributed systems with significant greenfield opportunity — implementing AI-first development practices, decoupling monolithic dependencies, and driving the technical standards that allow Fondue to scale alongside Postscript's core platform. This is a high-autonomy role that demands independent investigation, strong technical design instincts, and the ability to move fast without sacrificing system health. This position is fully remote and can be based in the US or Canada. Primary Duties Take ownership of the Fondue product and its underlying architecture — becoming the go-to technical expert for cashback, discounting, and incentives systems Independently investigate, design, and execute solutions across evolving distributed systems with a high degree of ambiguity Drive system decoupling and modularization — break down monolithic dependencies into flexible, independently deployable components Implement AI-first coding practices and tooling to reduce cognitive load, accelerate development cycles, and shorten time-to-market for new capabilities Help Fondue and other subsidiary products adopt Postscript's core tools, data formats, and technical standards to reduce cross-team friction Architect, build, and maintain highly available, scalable REST APIs for internal and external use Collaborate cross-functionally with finance and customer support teams — clear, proactive communication is essential in this role Contribute to process and technical improvements; someone who can quickly ramp on new systems and propose meaningful changes will thrive here Identify and eliminate single points of failure, improving knowledge redundancy and overall system resilience What We'll Love About You 4+ years experience building large-scale backend systems and APIs with Typescript experience (Go preferred; Python, Java also valued) You're experienced with autoscaling strategies for applications deployed on Kubernetes or other container orchestration platforms You're comfortable — and excited — using agentic coding tools like Claude Code, Cursor, or similar AI-first development tooling React experience strong nice to have You've worked on both 0-to-1 initiatives and complex existing systems, and know how to balance building new things with improving what's already there You have experience with relational and NoSQL databases, SQL, and thoughtful database modeling You're familiar with building and observing applications on AWS, and ideally Datadog You communicate with clarity and directness — cross-functional partners and async teams can count on you You're energized by distributed systems challenges and high-ownership environments You have strong instincts for technical trade-offs informed by both engineering best practices and business priorities What You'll Love About Us Salary range of USD $172,000–$203,000 base plus significant equity (we do not have geo-based salaries) High growth startup — plenty of room for you to directly impact the company and grow your career Work from home (or wherever) Fun — we're passionate and enjoy what we do Competitive compensation and opportunity for equity Flexible paid time off Health, dental, vision insurance For information about how we use your personal data, please see our U.S. Job Applicant Privacy Notice You are welcome here. Postscript is an ever-evolving place of equal employment for talented individuals.