What are the responsibilities and job description for the Full-Stack API Developer – Merchant Integration position at hyphenconnect?
Job Summary
We are hiring for an innovative crypto wallet and payment network startup who are looking for a Full-Stack API Developer to build and maintain merchant integration APIs, client portals, and SDKs for our crypto wallet app’s merchant payment system. You will develop backend services to support crypto-only payments via QR/NFC and POS, contributing to the January 2026 rollout. This remote role requires expertise in API development, merchant systems, and blockchain technology.
Responsibilities
- Design and develop merchant-facing APIs and SDKs to enable crypto payments via wallet app.
- Build and maintain merchant, admin, and customer portals for transaction management and reporting.
- Integrate backend services with smart contract-based payment systems for secure transactions.
- Collaborate with the Tech Lead and Integration Engineer to align APIs with merchant requirements.
- Ensure scalability, security, and performance of APIs for online and physical POS environments.
- Document APIs and SDKs for external developers and internal teams.
Qualifications
- 5 years of experience in full-stack development, with a focus on API and SDK development.
- Proven experience building merchant or client portals for payment systems (e.g., fintech, e-commerce).
- Strong proficiency in backend technologies (e.g., Node.js, Python, Go) and frontend frameworks (e.g., React, Vue.js).
- Familiarity with blockchain technology and crypto wallets (e.g., Solidity, Web3.js, Ethers.js).
- Experience with RESTful APIs and integration with payment gateways or POS systems.
- Ability to work remotely and align with Hong Kong/Singapore time zones.
- Bachelor’s degree in Computer Science, Engineering, or a related field (or equivalent experience).
Preferred Skills
- Experience with crypto payment gateways (e.g., Coinbase Commerce, BVNK) and QR/NFC systems.
- Knowledge of smart contract development and security (e.g., Hardhat, Foundry).
- Familiarity with POS hardware integration for in-store payments.
- Strong documentation skills for developer-facing APIs and SDKs.