Fullstack Engineer – Payment Integrations | Fully Remote

Rezerv Pte Ltd; United States; Remote; USD 94,000 - 125,000; Full time

Job summary

Rezerv is hiring a Fullstack Engineer to develop and maintain payment integrations for its booking, payments, and studio management platform. The role focuses on integrating third-party payment providers, including HitPay and PayPal, with REST APIs and webhooks.

You will work across frontend and backend using React.js, Next.js, C#, and ASP.NET Core to deliver secure, scalable payment functionality and reliable transaction processing.

Qualifications

• 3+ years of fullstack development experience.
• Strong React.js and Next.js experience.
• Strong C# and ASP.NET Core experience.
• Experience with REST APIs and webhooks.
• Experience with third-party API integrations, esp. payment gateways.
• Excellent debugging and problem-solving skills.

Responsibilities

• Integrate and maintain third-party payment gateways and APIs.
• Develop payment-related features across frontend and backend.
• Implement payment flows, webhooks, status updates, and refunds.
• Troubleshoot payment integration issues and API errors.
• Build secure, scalable payment integrations.
• Collaborate with product and engineering to deliver new features.
• Maintain integrations with HitPay, PayPal, and others.

Skills

React.js

Next.js

C#

ASP.NET Core

REST APIs

Webhooks

Payment gateway integration

Tools

HitPay

PayPal

Job description

Location: Fully Remote

Job Category: Information Technology (IT) & Software; Finance & Accounting; Banking & Insurance

Job Overview

Rezerv is hiring a Fullstack Engineer to develop and maintain payment integrations for its booking, payments, and studio management platform. The company supports more than 1,000 fitness, wellness, and sports businesses across Southeast Asia.

The role focuses on integrating third-party payment providers, including HitPay and PayPal, and maintaining reliable payment connections through REST APIs, webhooks, and other payment-related technologies. The successful candidate will work across frontend and backend systems to deliver secure, scalable, and dependable payment functionality.

This opportunity is suited to an experienced fullstack developer with expertise in React.js, Next.js, C#, and ASP.NET Core. Candidates with payment gateway integration experience will be preferred. The position also offers an opportunity to deepen technical expertise in payment systems, API integrations, transaction processing, and modern software development.

Key Responsibilities

• Integrate and maintain third-party payment gateways and payment APIs.
• Develop payment-related features across frontend and backend applications.
• Implement and maintain payment flows, webhooks, transaction status updates, and refund functionality.
• Troubleshoot payment integration issues, API errors, and transaction-related problems.
• Build and maintain reliable, secure, and scalable payment integrations.
• Collaborate with product and engineering teams to develop and deliver new payment features.
• Maintain integrations with providers such as HitPay, PayPal, and other third-party services.

Requirements & Qualifications

• At least 3 years of fullstack development experience.
• Strong experience with React.js and Next.js.
• Strong experience with C# and ASP.NET Core.
• Experience working with REST APIs and webhooks.
• Experience with third-party API integrations.
• Payment gateway integration experience is highly preferred.
• Strong troubleshooting, analytical, and problem-solving skills.

Technical environment:

• Frontend: React.js, Next.js
• Backend: C#, ASP.NET Core
• Integration technologies: REST APIs, webhooks, payment APIs
• Payment providers: HitPay, PayPal, and other third-party providers

Salary, Benefits & Career Growth

Compensation: Salary is paid in Singapore dollars (SGD). The specific salary range has not been disclosed.

The original job description does not specify additional employee benefits, training allowances, or certification support. Candidates should confirm these details directly with the employer.

The position provides opportunities to develop professional expertise in payment integrations, API development, transaction processing, and fullstack engineering. Experience in these areas can support long-term career growth in fintech, payment technology, and software engineering.