Payment Gateway API Integration for Mobile App

**Project Description**:
We are looking for an experienced developer to join our team and help build the core functionalities of our mobile app, **Club Online/Club offline**, which focuses on enabling users to club their purchases to avail of discounts. The app has a partially developed backend, with some functionalities already implemented by a previous developer. You will be responsible for completing the development by creating several key APIs.

**Responsibilities**:
- Continue the development from where the previous developer left off.
- Design and develop the following APIs:
1. **Subscription Model API**: Implement subscription plans, including free and premium tiers, with corresponding benefits.
2. **Payment Method API**: Integrate a secure payment gateway for transactions within the app.

**Requirements**:
- Proven experience in API development and integration, especially in mobile app backends.
- Strong knowledge of RESTful APIs, security protocols, and authentication methods.
- Experience in payment gateway integration (e.g., Stripe, Razorpay, PayPal).

**Preferred Skills**:
- Experience with subscription-based models for mobile applications.
- Familiarity with React Native or mobile app development frameworks.
- Knowledge of Indian payment systems and regulations is a plus.