About the role

Role Overview

Senior Software Engineer (Back-End)

As a Sr. Software Engineer, Back-End, you will own critical systems at Rebuy, primarily the billing and payments infrastructure that drives merchant charges, partner payouts, and balance flows across the product suite. You’ll also contribute to platform expansion (APIs, ETL, reporting infrastructure) and a near-term migration from CodeIgniter 2 to CodeIgniter 4.

Responsibilities

Billing & Payments Architecture:
- Design and build a centralized billing system for merchant billing, partner payments, and customer-facing charges.
- Architect integration layers to apply payment balances across Rebuy services.
- Solve complex financial engineering problems at scale using PHP and Go.
Build Robust APIs:
- Design and implement secure, well-structured APIs in PHP and Go for billing events, payment processing, and financial data flows (including Shopify integrations).
Legacy Modernization (High Priority):
- Lead and contribute to migrating CodeIgniter 2 → CodeIgniter 4.
- Deliver this migration as a near-term priority with real business dependencies.
Agentify the Platform (AI Automation):
- Work with product/engineering to identify opportunities where AI agents automate workflows and provide merchant guidance.
- Build backend systems (APIs, data pipelines, event hooks) to enable intelligent automation.
Platform Breadth & Reliability:
- Support additional areas such as partner portal, data ETL pipelines, reporting APIs, and data-flow infrastructure.
Engineering Best Practices:
- Establish, document, and promote backend engineering best practices.
- Lead initiatives to standardize frameworks and improve development practices.

Requirements

Deep backend expertise with PHP.
Strong experience with Go.
Ability to architect and implement secure backend APIs and integrations.
Hands-on experience with CodeIgniter and strong judgment for legacy modernization (migration to CodeIgniter 4).
Comfort working on high-stakes, revenue-impacting systems (billing runs daily).

Nice-to-Haves

Experience with data ETL pipelines and reporting infrastructure.
Familiarity with AI automation/agent-driven workflows and event-driven backend design.
Experience integrating with Shopify.

About Rebuy, Inc.

Rebuy, Inc. builds intelligent, personalized shopping experiences for DTC brands. The company is a fully remote team focused on engineering systems that power billing, payments, APIs, data pipelines, and commerce platform infrastructure.

Sr Software Engineer B E

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