Go Wallet System — Production-Grade Digital Wallet API in Pure Go

A fully functional, secure, and atomic digital wallet backend built entirely in pure Go — zero web frameworks (no Gin, no Echo, no Fiber).

This is how real payment systems work under the hood.

Live Postman Demo

(Full collection link below)

Core Features

• User registration & login with JWT authentication
• Atomic P2P money transfers (with row-level locking)
• Top-up wallet balance
• Real-time balance inquiry
• Complete transaction history per user
• Full input validation & error handling
• Rate limiting, CORS, structured logging
• Database migrations
• Clean, scalable, layered architecture

Tech Stack

Layer	Technology
Language	Go (pure net/http)
Database	PostgreSQL + sqlx
Auth	JWT (self-implemented)
Architecture	Domain-Driven Design (DDD) inspired
Concurrency	Database transactions + FOR UPDATE
No dependencies	Only standard library + sqlx

REST API Endpoints

Method	Endpoint	Description	Auth
POST	/users	Create account	Public
POST	/users/login	Login → JWT	Public
GET	/wallets/my-balance	Get current balance	JWT
POST	/wallets/topup	Add money	JWT
POST	/wallets/transfer	Send money to another user	JWT
GET	/transactions	Full transaction history	JWT

Key Engineering Concepts Implemented

• Atomic transactions using WithTx + FOR UPDATE row locking
• Preventing race conditions in financial operations
• Clean separation of concerns (Domain → Service → Repository → Handler)
• Dependency inversion (interfaces in domain layer)
• Secure JWT implementation from scratch
• Structured error handling with custom domain errors
• Middleware chain: Logger → CORS → Rate Limit → Auth
• Production-ready response utilities

Project Structure (Clean & Scalable)

wallet/
├── cmd/ 
├── domain/           # Pure entities & business rules
├── migrations/
├── wallet/           # Application use cases 
├── user/ 
├── repo/             # Database implementations
├── rest/handlers/walletB/  # HTTP delivery layer
├── rest/middlewares/ # Auth, CORS, Logger, RateLimiter
├── infra/db/         # Connection + migrations
└── util/             # Response helpers, JWT, etc.
├── main.go           # main file

Run Locally
Bash: 
git clone https://github.com/niloy104/VaultGo.git
cd wallet
cp .env.example .env
go run main.go

Server: http://localhost:4000


Postman Collection
Download Full Postman Collection
View in Postman (link after upload)
Future Roadmap


Future Roadmap
Admin dashboard
Transaction search & filters
Docker + PostgreSQL compose
Unit & integration tests
WebSocket real-time balance updates

License
MIT © niloy104