Senior Backend Engineer & Tech Lead: Multi-Tenant Payments Platform (Node.js, Authorize.net)

We're building a modern platform around a legacy Windows point-of-sale system (VB6 on SQL Server): a cloud backend, customer apps, a merchant portal, a platform admin portal and integrations with Authorize.net and in-store card terminals. A separate developer owns the VB6/SQL Server connector, and another owns the card terminals. We're hiring for two backend roles, and you can apply for either: 1. Technical lead and platform architect: Node.js/NestJS (or .NET), multi-tenant SaaS, role-based access, durable messaging (Kafka or RabbitMQ), test strategy and code quality. 2. Payments and backend engineer: Authorize.net (Accept Hosted, webhooks, transaction lookups), payment ledgers, idempotency, reconciliation and refunds. What matters most: payments that post exactly once, safe recovery when a result is unknown, audit logs, and clean, documented code. Engagement: about 30 to 40 hours per week for 7 to 9 months, starting late November, delivered in phases. To apply, tell us: 1. Which role you're applying for 2. One or two production systems you built that are closest to this, and what your role was 3. Your hourly rate and the hours per week you can commit from late November Proposals without specific production experience will not be considered.