Freelance Developer for QuickBooks Online Payment Integration App

We are looking for an experienced freelance developer to design and build a cross-platform app that integrates seamlessly with QuickBooks Online. The app should support efficient payment processing, invoicing, and recurring billing functionalities for businesses. It must be compatible with web, iOS, and Android platforms.

Key Features:

- Integration with QuickBooks Online using the QuickBooks API.
- Support for multiple payment methods, including credit cards and ACH/e-check payments.
- Automated data synchronization with QuickBooks Online to prevent duplicate entries.
- Flexible pricing options, including surcharges and recurring billing features.
- User-friendly interface with customizable checkout pages optimized for mobile and desktop usage.
- Full compatibility and functionality across web, iOS, and Android devices.

Requirements:
- Strong expertise in QuickBooks API and payment gateway integration.
- Proven experience in developing cross-platform apps for web, iOS, and Android.
- Knowledge of secure payment processing and compliance with industry standards.
- Excellent communication and problem-solving skills.

Preferred Skills:
- Familiarity with SaaS app development.
- Experience with accounting software integration.

Deliverables:
- Fully functioning, cross-platform app with QuickBooks Online integration.
- Comprehensive documentation for app usage, setup, and maintenance.

Timeline:
Please provide the time you need to complete this project

Please provide:
- Portfolio with relevant projects.
- A brief proposal outlining your approach to development.
- Your availability and estimated timeline for delivery.