Sudipta Singh

Java Backend Developer

Kolkata, India 0+ yrs exp 80 · Excellent

About

Java Backend Developer with strong foundations in Core Java, OOP, SQL and backend development, currently working as a Java Developer Trainee at HulkHire Tech. Developing a real-time PayPal Payment Integration System using Spring Boot, Microservices and REST APIs, with hands-on experience in payment workflows, API integration, authentication, exception handling, database persistence, debugging and testing. Familiar with Kafka, Docker, AWS, Git, Maven and Agile/Scrum, with a focus on building maintainable, reliable and scalable backend services.

Skills & Expertise (38)

RESTful APIs Advanced

8.5/10

0.5

Years Exp

Microservices Architecture Advanced

8.5/10

0.5

Years Exp

AWS RDS Advanced

8.1/10

0.5

Years Exp

Debugging & troubleshooting Advanced

8.1/10

0.5

Years Exp

AWS RDS Advanced

8.1/10

0.5

Years Exp

AWS EC2 Advanced

8.1/10

0.5

Years Exp

Debugging & troubleshooting Advanced

8.1/10

0.5

Years Exp

Core Java Advanced

8.1/10

0.5

Years Exp

AWS EC2 Advanced

8.1/10

0.5

Years Exp

OAuth 2.0 Advanced

8.1/10

0.5

Years Exp

OOP Advanced

8.1/10

0.5

Years Exp

Spring JDBC Advanced

8.1/10

0.5

Years Exp

JSON Advanced

8.1/10

0.5

Years Exp

Micrometer Intermediate

7.5/10

0.5

Years Exp

Micrometer Intermediate

7.5/10

0.5

Years Exp

Logback Intermediate

7.5/10

0.5

Years Exp

SLF4J Intermediate

7.5/10

0.5

Years Exp

Docker Compose Intermediate

7.5/10

0.5

Years Exp

AWS Secrets Manager Intermediate

7.5/10

0.5

Years Exp

Data Structures & Algorithms Intermediate

7.5/10

0.5

Years Exp

DBeaver Intermediate

7.5/10

0.5

Years Exp

Eclipse Intermediate

7.5/10

0.5

Years Exp

Swagger UI Intermediate

7.5/10

0.5

Years Exp

cURL Intermediate

7.5/10

0.5

Years Exp

Apache Kafka Intermediate

7.5/10

0.5

Years Exp

Logback Intermediate

7.5/10

0.5

Years Exp

SLF4J Intermediate

7.5/10

0.5

Years Exp

Docker Compose Intermediate

7.5/10

0.5

Years Exp

AWS Secrets Manager Intermediate

7.5/10

0.5

Years Exp

Eureka Service Registry Intermediate

7.5/10

0.5

Years Exp

Circuit Breaker Intermediate

7.5/10

0.5

Years Exp

DBeaver Intermediate

7.5/10

0.5

Years Exp

Eclipse Intermediate

7.5/10

0.5

Years Exp

Swagger UI Intermediate

7.5/10

0.5

Years Exp

cURL Intermediate

7.5/10

0.5

Years Exp

Code Coverage Intermediate

7.5/10

0.5

Years Exp

Basic Authentication Intermediate

7.5/10

0.5

Years Exp

Transaction Management Intermediate

7.5/10

0.5

Years Exp

Work Experience

Java Developer Trainee

HulkHire Tech

Aug 2026 - Present

Analyzed PayPal Standard Checkout Order APIs and contributed to the technical integration approach. Developed PayPal Provider Service using Spring Boot and integrated PayPal Create Order and Capture Order APIs. Implemented payment status tracking across the payment lifecycle with accurate transaction-state transitions. Secured PayPal API communication using OAuth 2.0 Client Credentials, Basic Authentication and access tokens. Implemented centralized exception handling and custom error codes for consistent backend error responses. Applied Microservices and Circuit Breaker patterns for modular and fault-tolerant service communication. Used Spring JDBC with MySQL for payment data persistence and transaction handling. Integrated Apache Kafka for asynchronous payment-event communication and decoupled status updates. Applied Factory, Strategy and Builder design patterns to improve code modularity and maintainability. Containerized services using Docker/Docker Compose and worked with AWS EC2, RDS and Secrets Manager. Developed unit tests using JUnit and Mockito and participated in Agile/Scrum sprint activities.