Digital Wallet API (Laravel 12)

A backend-only RESTful API for a fintech-style digital wallet system, designed with correctness, security, and scalability in mind.

This project implements wallet management, money transfers, fraud detection, admin review workflows, and aggregated statistics with Redis caching.

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Features

Core Functionality

• Token-based authentication using Laravel Sanctum
• Multi-currency wallet support (TRY, USD, EUR)
• Transactions: Deposit, Withdrawal, Transfer, Refund
• Atomic balance updates with database transactions and row-level locking
• Idempotency support for transfer requests
• Fee calculation using Strategy Pattern

Fraud & Risk Management

• Rule-based fraud detection (Pipeline / Chain of Responsibility)
• Automatic transaction flagging
• Manual review workflow (pending_review)
• Multiple configurable fraud rules

Admin Capabilities

• Review, approve, reject suspicious transactions
• Aggregated statistics endpoint
• Redis-based caching for heavy queries

Performance & Infrastructure

• Redis for cache and rate limiting
• Pagination on all list endpoints
• Artisan operational commands

Testing

• Unit tests for fee logic
• Feature tests for transfer and auth flows

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Tech Stack

• PHP 8.3+
• Laravel 12
• MySQL / MariaDB
• Redis
• PHPUnit

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Requirements

• PHP 8.3+
• Composer
• MySQL or MariaDB
• Redis Server
• Git

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Installation

git clone https://github.com/sabermand/wallet.git
cd wallet
composer install
cp .env.example .env
php artisan key:generate
php artisan migrate

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Redis Setup

.env:

CACHE_STORE=redis
REDIS_HOST=127.0.0.1
REDIS_PORT=6379

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Run

php artisan serve

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Tests

php artisan test

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Artisan Commands

php artisan stats:refresh-cache

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📡 API Endpoints (v1) — With Request & Response Examples

Global Headers

Accept: application/json
Content-Type: application/json
Authorization: Bearer {SANCTUM_TOKEN}

Transfer endpoints also require:

Idempotency-Key: {unique-key}

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Auth

Register

POST /api/v1/auth/register

{
  "name": "Hamid",
  "email": "hamid@example.com",
  "password": "Pass1234!",
  "password_confirmation": "Pass1234!"
}

Login

POST /api/v1/auth/login

{
  "email": "hamid@example.com",
  "password": "Pass1234!"
}

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Wallets

Create Wallet

POST /api/v1/wallets

{
  "currency": "TRY"
}

List Wallets

GET /api/v1/wallets

Wallet Balance

GET /api/v1/wallets/{wallet_id}/balance

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Transactions

Deposit

POST /api/v1/transactions/deposit

{
  "wallet_id": "WALLET_UUID",
  "amount": 500
}

Withdraw

POST /api/v1/transactions/withdraw

{
  "wallet_id": "WALLET_UUID",
  "amount": 200
}

Transfer (Idempotent)

POST /api/v1/transactions/transfer

{
  "source_wallet_id": "WALLET_UUID_1",
  "destination_wallet_id": "WALLET_UUID_2",
  "amount": 100
}

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Admin

Pending Review

GET /api/v1/admin/transactions/pending-review

Approve Transaction

POST /api/v1/admin/transactions/{id}/approve

Reject Transaction

POST /api/v1/admin/transactions/{id}/reject

Statistics (Cached)

GET /api/v1/admin/statistics