I'm looking for a comprehensive invoice and billing software solution that includes a form builder, integrates with payment gateways, and supports multiple user roles. Key Requirements: - Form builder for customizable billing forms - Subscription management features - Integration with UPI gateway and SmartUpiQR - User role management: Admin, Editor, Viewer, User Ideal Skills & Experience: - Proficiency in software development for desktop platforms (Windows, MacOS, Linux) - Experience with payment gateway integration, especially UPI - Strong backend development skills to manage user roles and permissions - UI/UX design experience for intuitive form building and navigation Please provide examples of similar projects completed and estimated timelines.