Building a Simple Bank App API with Spring Boot and Spring Data JPA

When learning backend development, one of the best ways to practice is by building something practical and relatable. For me, that turned out to be a Bank App API — a Spring Boot project where users can create accounts, deposit and withdraw money, check balances, and even close accounts.

This project gave me hands-on experience with Spring Boot, Spring Data JPA, and REST API design, while also teaching me how to think about real-world requirements like account numbers and user authentication.

🛠 Tech Stack

Spring Boot – for building the REST API.

Spring Data JPA – for interacting with the database.

Maven – build and dependency management.

Database – works with relational databases like MySQL (but could also run on H2 for testing).

📌 Features Implemented

The application exposes endpoints under /account. Here’s what you can do:

Create an account
POST /account – Add a new account to the system.

Get account by account number
GET /account/{accountNumber} – Fetch details for a specific account.

Get all accounts
GET /account – Retrieve all stored accounts.

Deposit money
PUT /account/deposit/{accountNumber}/{amount} – Increase the account balance.

Withdraw money
PUT /account/withdraw/{accountNumber}/{amount} – Deduct from the account balance.

Close an account
DELETE /account/delete/{id} – Remove an account from the system.

Here’s a snippet from the controller:

public class AccountController {

    @Autowired
    AccountService service;


    @PostMapping
    public ResponseEntity<Account> createAccount(@RequestBody Account account){
        Account createAccount =service.createAccount(account);
        return ResponseEntity.status(HttpStatus.CREATED).body(createAccount);
    }

    @GetMapping("/{accountNumber}")
    public Account getAccountDetailsByAccountNumber(@PathVariable Long accountNumber) {
        Account getAccountDetail = service.getAccountDetailsByAccountNumber(accountNumber);
        return getAccountDetail;
    }

    @GetMapping
    public List<Account> getAllAccountDetails() {
        List<Account> getAccountDetail = service.getAllAccountDetails();
        return getAccountDetail;
    }

    @PutMapping("/deposit/{accountNumber}/{amount}")
    public Account depositAmount(@PathVariable Long accountNumber,@PathVariable Double amount){
        Account account = service.depositAmount(accountNumber,amount);
        return account;
    }

    @PutMapping("/withdraw/{accountNumber}/{amount}")
    public Account withdrawAmount(@PathVariable Long accountNumber,@PathVariable Double amount){
        Account account = service.withdrawAmount(accountNumber,amount);
        return account;
    }

    @DeleteMapping("/delete/{accountNumber}")
    public ResponseEntity<String> closeAccount(@PathVariable Long accountNumber){
        return ResponseEntity.status(HttpStatus.NO_CONTENT).body(service.closeAccount(accountNumber));
    }
} 

⚡ Challenges & Learning

Building this project gave me valuable practice with:

• Structuring a Spring Boot project with controllers, services, and repositories.

• Working with Spring Data JPA to simplify database operations.

• Designing clean and RESTful API endpoints.

• Testing endpoints using Postman.

I also realized how important it is to think ahead about real-world requirements. For example, account numbers should be standardized (e.g., 10-digit numbers) and authentication is needed to secure operations like deposit and withdrawal.

🔮 Future Improvements

This project is still growing, and here’s what I plan to add next:

• Unique 10-digit account numbers (instead of relying on auto-generated IDs).

• Login and Signup functionality, powered by Spring Security.

• Improved error handling and validation (e.g., prevent overdrawing).

Transaction history and account statements.

🎯 Conclusion

The Bank App project may be simple, but it demonstrates core backend concepts:

• Building REST APIs with Spring Boot.

• Using JPA for database operations.

• Structuring an application into layered components.

It’s a solid step in my Spring Boot journey, and I plan to keep improving it as I learn more about authentication, security, and production deployment.

🔗 Check it out on GitHub: Bank-App-Spring-Boot

Comments

[ALI]

Finally, a Bank App where the AI won’t judge me for my spending habits… though I’m still nervous about the withdraw endpoint—what if it starts suggesting I save more?
Loving the Spring Boot + JPA combo though, feels like I’m teaching my code to handle my adulting for me!