The Company Youâll JoinAt Rebuy, weâre on a mission to revolutionize shopping with intelligent, personalized experiences that wow customers around the globe. As a fully remote team, we power some of the fastest-growing DTC brands like Aviator Nation, Liquid Death, Magic Spoon, Blenders, Laird Superfoods, Primal Kitchen, and many more.We believe in ownership, drive, and empathy, and strongly uphold that every team member plays a vital role in shaping the future of intelligent commerce. Our culture thrives on collaboration, creativity, and genuine passion. We donât just build great tech - we build lasting partnerships, a strong community, and a place where people love to work.The Problems Youâll SolveRebuy and its team members continually strive to create a high-spirited, intentional work environment that stresses performance, productivity, collaboration, and merit.As a Sr. Software Engineer, Back-End, youâll own some of the most consequential systems at Rebuy. Your primary anchor is our billing and payments infrastructure â the engine that determines how merchants are charged, how partners get paid, and how financial balances flow across our entire product suite. This is genuinely complex financial engineering. It requires deep PHP and Go expertise, careful architecture, and judgment that no automated tool can replicate. Merchant billing runs daily, touches real revenue, and demands someone who understands both the technical and business dimensions of every decision.Alongside billing, youâll grow into a broader platform portfolio â the partner portal, data ETL pipelines, customer-facing APIs, and reporting infrastructure that power the business. And in the near term, youâll play a critical role in a significant technical migration: moving our legacy Code Igniter 2 codebase to Code Igniter 4, including work tied to increasing our enterprise market share. This migration requires hands-on PHP expertise and cannot be deferred.You wonât be handed a sprawling list of things you must do on day one. Youâll be trusted to grow into this role â and rewarded when you do.Billing & Payments Architecture: Design and build Rebuyâs centralized billing system that handles merchant billing, partner payments, and customer-facing charges. Architect the integration layer that allows payment balances to be applied across Rebuyâs full suite of services. Tackle genuinely complex financial engineering challenges with PHP and Go at scale.Build Robust APIs: Design and implement secure, well-structured APIs in PHP and Go to power billing events, payment processing, and financial data flows across our platform and Shopify integrations.Legacy Modernization: Lead and contribute to the migration of our Code Igniter 2 codebase to Code Igniter 4. This is high-priority, near-term work with real business dependencies â including enterprise partnership commitments â and requires a PHP engineer with the experience and judgment to do it right.Agentify the Platform: Partner with product and engineering to identify where AI agents can automate workflows, surface insights, and guide merchants through our product. Build the backend systems â APIs, data pipelines, and event hooks â that enable intelligent automation. This is genuinely new territory and one of the most exciting growth vectors for Rebuyâs product.Platform Breadth: Our team owns more than billing and payments â we also support a partner portal, data ETL pipelines, customer-facing reporting APIs, and the infrastructure that makes data flow reliably across the business. You wonât be responsible for all of it on day one, but youâll have genuine opportunities to grow into the areas that most interest you. Engineers here donât get siloed; they get context.Engineering Best Practices: Contribute significantly to the engineering culture at Rebuy by establishing, documenting, and promoting best practices. Lead initiatives to introduce and standardize frameworks and tools that increase development efficiency and maintainability.Security & Compliance: Stay current with the latest security trends, vulnerabilities, and best practices as they apply to billing and payment systems. Champion security-first engineering across authentication, authorization, data encryption, and compliance considerations in everything you build.PHP Technical Leadership: Serve as a key technical anchor for PHP across the engineering organization. Rebuyâs codebase has significant PHP depth and relatively few engineers with that expertise. Youâll lead code reviews, share knowledge actively, and help raise the PHP competency of the broader team.Quality Assurance: Conduct quality checks on deliverables to ensure code, setup, and configurations meet expected results. Ensure that all features meet high standards of quality and performance before deployment.Team Collaboration: Engage actively in building a strong team culture. Work closely with the Product Owner, Engineering Manager, and peers across billing, payments, partner tools, and data infrastructure to define requirements, estimate effort, and drive solutions forward. This is a team where your voice matters â you wonât just be handed tickets. Assist the Support team in triaging and resolving high-priority production issues.Technologies We Use:AI: Anthropic Enterprise Claude Code / Co-work, Cursor, Adhoc AI tools budget.Frontend Technologies: React, TypeScript, GraphQL, VueJS, AngularBackend technologies: PHP, GO, MySQL, BigTable, ElasticsearchOther Tools: Jira, Bitbucket, Confluence, Google Suite, Slack, One Password, NotionWho You AreWeâre stoked to meet you and get to learn more about you, your experience and your interest in joining our team.The Hard Skills:Experience building or maintaining billing, payments, or financial systems â including working with payment processors, subscription engines, invoicing pipelines, or similar financial infrastructure in a production SaaS environment.Educational background in CS // Engineering or a similar area.5+ years of hands-on experience building backend applications with PHP and Go, with a proven track record of delivering complex, high-traffic systems.Experience designing and implementing secure, scalable, and maintainable RESTful APIs in PHP and Go, with a deep understanding of API design patterns, versioning, and performance optimization.Experience with cloud-based technologies, preferably GCP.Strong understanding of a performant SaaS environment.Experience in a Scrum/Agile environment.Experience with the Atlassian suite, including Jira and Bitbucket.Solid understanding of security fundamentals as they apply to backend and financial systems â including secure coding practices, authentication/authorization patterns, data encryption, and awareness of current vulnerability trends (e.g. OWASP Top 10)The Soft Skills:A collaborative mindset and work approach with the ability to lead projects and mentor others.The ability to thrive in a fast-paced environment with a high level of autonomy and responsibilities.Excellent communication skills, especially being able to explain technical concepts to both technical and non-technical audiences.Genuinely curious about the intersection of engineering and business. You care about the downstream impact of what you build â not just that the code works, but that it moves the company forward.Who Youâll Meet WithNow letâs get into who youâll meet during our interview process! After you submit your application and itâs been reviewed by our team, we will reach out to you inviting you to meet with us. From there, you can expect an interview process similar to this:An introductory call with someone from the Talent Acquisition team for about 30 min.Interview with the Hiring Manager to learn more about you and answer your questions about Rebuy and this roleA coding challenge and white boarding exercise to show us your skillset during a live panel interview with a few team members.Short final interview with our CEO and COO where youâll get to learn more about Rebuy.The Perks Youâll EnjoyRebuy is a fully remote company across the U.S. and Canada that aims to provide all of our team with the resources, support and flexibility they need to thrive in their roles.Team: Weâve got the best, brightest, most brilliant team members who are excited to meet you! We also like to think we have a good sense of humor.Remote Work: With a strong internet connection, youâre able to work from anywhere within the U.S. and Canada.PTO: We offer a flexible vacation policy, generous holiday schedule, parental leave and sick policy. Thereâs other policies too like a birthday holiday!Amazing Benefits: 100% free health, dental, and insurance for you and your family. Donât worry, thereâs even more!Retirement Plans: For our U.S. employees we offer 401(k) retirement plans and for our Canadian employees we offer a TFSA and RRSP retirement plans. Youâll also enjoy a 3% contribution of your gross salary, no matter where youâre located!Our compensation reflects the cost of labor across several U.S. geographic markets, and we pay differently based on those defined markets. The U.S. pay range for this position is $130,000 - $180,000 USD annually. Pay within this range varies by work location and may also depend on job-related knowledge, skills, and experience. Your recruiter and hiring manager can share more about the specific salary range for the job location during the hiring process.Disclosures:Equal Opportunity StatementRebuy, Inc. is proud to be an Equal Employment Opportunity employer. We do not discriminate based on gender, race or color, ethnicity or national origin, age, disability, religion, sexual orientation, gender identity or expression, veteran status, or any other applicable characteristics protected by law.Rebuy, Inc. aims to make rebuyengine.com accessible to any and all users. If you have a disability or special need that requires accommodation to navigate our website or complete the application process, email hr@rebuyengine.com.Please mention the word **SUPPORTER** and tag RMjAzLjExMC4yNDcuNTM= when applying to show you read the job post completely (#RMjAzLjExMC4yNDcuNTM=). This is a beta feature to avoid spam applicants. Companies can search these words to find applicants that read this and see they're human.