MiniPay - Lightweight Payment Orchestration API

A production-grade Go REST API for managing payments with Stripe-inspired architecture. Implements charge creation, refunds, webhook delivery, idempotency, and transaction persistence using SQLite.

Features

• Charge Creation: Atomic transaction creation with unique idempotency keys
• Refunds: Revert completed transactions with balance recalculation
• Balance Tracking: Real-time balance calculation with refund deductions
• Webhook Delivery: Async webhook processing with exponential backoff retries
• Idempotency: In-memory and DB-backed idempotency to prevent duplicate processing
• Metrics: Real-time metrics endpoint for monitoring charges, refunds, and webhook health
• Concurrency Safe: Thread-safe using sync.RWMutex and atomic operations
• Health Checks: Built-in health endpoint for liveness probes

Local Development

1. Clone the repository:

git clone https://github.com/vaidikcode/minipay.git
cd minipay

2. Download dependencies:

go mod download

3. Run the application:

go run main.go

The server will start on http://localhost:8080

API Endpoints

Create Charge

curl -X POST http://localhost:8080/api/v1/charges \
  -H "Content-Type: application/json" \
  -H "Idempotency-Key: idem-unique-key-123" \
  -d '{
    "amount": 1000,
    "currency": "usd",
    "customer": "cust_123"
  }'

Refund Transaction

curl -X POST http://localhost:8080/api/v1/refunds \
  -H "Content-Type: application/json" \
  -d '{
    "transaction_id": "txn_550e8400e29b41d4a716446655440000"
  }'

Get Balance

curl http://localhost:8080/api/v1/balance

Metrics

curl http://localhost:8080/metrics

Health Check

curl http://localhost:8080/health

Testing

Run the full test suite:

go test -v ./...

Run with coverage:

go test -v -coverprofile=coverage.out ./...

Docker

Build and run with Docker:

docker build -t minipay:latest .
docker run -p 8080:8080 minipay:latest