Core Banking API

A production-style banking backend built with Spring Boot, JWT security, and MySQL.

This project models a real-world core banking flow:

User -> Account -> Transaction -> Notification

Why This Project

This codebase is designed to demonstrate how financial systems are built with:

• clean layered architecture
• secure authentication and authorization
• data integrity during money movement
• traceable transaction records

Key Features

• User registration with validation and BCrypt password hashing
• JWT-based login with stateless API security
• Account creation and account listing per user
• Money operations:
  • deposit
  • withdraw
  • transfer between accounts
• Notification center with unread count and mark-as-read flow
• Global exception handling with consistent API error responses

Architecture

Layered architecture is used throughout the project:

Controller -> Service -> Repository -> Entity

Highlights:

• DTO-based request/response contracts
• JPA repositories for persistence
• Service-layer business rules for banking operations
• Access guard checks to prevent cross-user data access
• Pessimistic locking for safe concurrent transfers

Tech Stack

• Java 17
• Spring Boot 3.5
• Spring Security
• JWT (jjwt)
• Spring Data JPA / Hibernate
• MySQL
• Maven
• SpringDoc OpenAPI (Swagger)

API Snapshot

Auth and Users

POST   /api/v1/users                  Register user
POST   /api/v1/auth/login             Login and get JWT

Accounts

POST   /api/v1/users/{userId}/accounts    Create account
GET    /api/v1/users/{userId}/accounts    List user accounts

Transactions

POST   /api/v1/accounts/{accountId}/deposit       Deposit money
POST   /api/v1/accounts/{accountId}/withdraw      Withdraw money
POST   /api/v1/accounts/{accountId}/transfer      Transfer money
GET    /api/v1/accounts/{accountId}/transactions  Account transaction history

Notifications

GET    /api/v1/users/{userId}/notifications
GET    /api/v1/users/{userId}/notifications/unread-count
PATCH  /api/v1/users/{userId}/notifications/{notificationId}/read

Security Model

• Public endpoints:
  • POST /api/v1/users
  • POST /api/v1/auth/login
• All other endpoints require Authorization: Bearer <token>
• Access is scoped to the authenticated user via guard checks
• Disabled users and invalid/expired tokens are blocked

Getting Started

1. Clone

git clone https://github.com/reachraviraju/CoreBanking-API.git
cd CoreBanking-API

2. Configure Environment

The app reads credentials from environment variables with safe defaults for local dev:

• MYSQL_USER (default: root)
• MYSQL_PASSWORD (default: admin)
• JWT_SECRET (must be at least 32 bytes in production)
• JWT_EXPIRATION_MS (default: 86400000)

3. Run the Application

./mvnw spring-boot:run

On Windows:

.\mvnw.cmd spring-boot:run

4. Open API Docs

• Swagger UI: http://localhost:8080/swagger-ui.html
• OpenAPI JSON: http://localhost:8080/v3/api-docs

Local Testing

Run tests:

./mvnw test

The context test is configured with in-memory H2 so tests do not depend on local MySQL availability.

Example Flow

1. Register a user
2. Login to receive JWT
3. Create an account for that user
4. Deposit funds
5. Withdraw or transfer funds
6. Read notifications and mark them as read

Future Improvements

• Role-based authorization (admin/user roles)
• Audit trail enrichment for compliance-style reporting
• Rate limiting and abuse protection
• Idempotency support for payment-like operations

Author

Ravi Raju Chintalapudi