Full Stack Java Developer

*Job Overview:* We are looking for a highly skilled *Full Stack Java Developer* to join our technology team at *SP TRANSACTION HUB TECHNOLOGY PRIVATE LIMITED. The candidate will be responsible for the **end-to-end development and integration of payment gateway systems*. This is a core technical role with a high impact on our fintech infrastructure.  *Key Roles and Responsibilities:* * Design, develop, and maintain robust, scalable backend services and APIs using *Java (Spring Boot)*. * Develop responsive and dynamic user interfaces using *React.js / Angular / HTML5 / CSS3 / JavaScript*. * Integrate third-party banking APIs, UPI, payment gateways (Razorpay, Cashfree, PayU, etc.), and internal financial systems. * Implement secure payment flows, tokenization, encryption, and fraud prevention mechanisms. * Manage full project lifecycle from design to deployment, including unit testing and performance tuning. * Collaborate with product managers, designers, and QA teams to ensure smooth execution of features. * Write clean, well-documented, and reusable code with proper version control (Git). * Optimize applications for maximum speed, scalability, and reliability. * Handle database design and development with *MySQL / PostgreSQL / MongoDB*. * Troubleshoot and resolve bugs, production issues, and bottlenecks in real-time systems. * Stay updated on new technologies, trends, and compliance standards in the fintech/payment industry. *Required Technical Skills:* * *Languages & Frameworks:*  * Core Java, Spring Boot, Hibernate  * HTML5, CSS3, JavaScript, TypeScript  * React.js or Angular (preferred) * *Databases:*  * MySQL, PostgreSQL, or MongoDB * *Tools & Technologies:*  * Git, Maven, Jenkins, REST APIs, Swagger  * Postman, Docker (optional) * *Knowledge of:*  * Payment gateway protocols: UPI, IMPS, NEFT, RTGS, QR  * Authentication and Security: JWT, OAuth2, SSL  * PCI DSS compliance and encryption methods *Preferred Qualifications:* * Bachelor's/Master’s degree in Computer Science, Engineering, or related field. * Prior experience with any payment gateway provider or fintech startup is a *strong plus*. * Understanding of digital transaction flows, KYC, merchant onboarding, and API-based banking systems. * Strong analytical, problem-solving, and communication skill