XPay
XPay's personal visa-free payment system is completely free
...The open-source repository contains the version 2.0 code and supports payment workflows for services such as Alipay, WeChat, QQ Wallet, and UnionPay-style collection methods. Orders can carry identifiers that help match incoming transfers to individual transactions. Its unsigned personal-payment workflow relies on user review and email-based confirmation instead of continuously monitoring payment apps. Mobile payment scenarios can be integrated with H5 pages, applications, and mini programs. The backend uses Spring Boot, Spring MVC, Spring Data JPA, MySQL, Redis, Thymeleaf, and Swagger. ...