I’m building a focused invoicing module to sit at the heart of my small-business finance workflow. The scope is intentionally narrow: no payroll, no general expense tracking—just rock-solid invoice creation, delivery, and follow-up. Here’s what matters most to me: • Payment reminders must go out automatically by both email and SMS. Timing rules (e.g., 7-day, due-day, 3-day-overdue) need to be configurable from an admin panel. • The system has to plug cleanly into existing accounting software. I currently work with QuickBooks Online, but I’d like the code structured so connectors for Xero or FreshBooks can be slotted in later with minimal refactor. RESTful APIs and webhooks are preferred. • Standard invoice features—client database, line-item editor, tax and discount fields, PDF generation—should feel frictionless on desktop and mobile browsers. Acceptance will be based on: 1. A working web app (Laravel, Node, or similar) deployed to my staging server. 2. Successful email (SMTP) and SMS (Twilio or comparable) dispatch of reminder schedules. 3. Two-way sync of invoice status with QuickBooks (create, update, paid). 4. Clean codebase with README and basic unit tests. If you’ve built SaaS or SPA invoicing tools before and can turn this around quickly, let’s talk.