since 1983, developing the free unix style operating system gnu, so that computer users can have the freedom to share and improve the software they use.

sourceforge provides free & fast open source software downloads and development, and business software reviews and comparisons featuring the largest open source and business software directory.

red hat is the world’s leading provider of enterprise open source solutions, including high-performing linux, cloud, container, and kubernetes technologies.

stack overflow is the largest, most trusted online community for developers to learn, share​ ​their programming ​knowledge, and build their careers.

github is where over 100 million developers shape the future of software, together. contribute to the open source community, manage your git repositories, review code like a pro, track bugs and features, power your ci/cd and devops workflows, and secure code before you commit it.

博客园是一个面向开发者的知识分享社区。自创建以来，博客园一直致力并专注于为开发者打造一个纯净的技术交流社区，推动并帮助开发者通过互联网分享知识，从而让更多开发者从中受益。博客园的使命是帮助开发者用代码改变世界。

掘金是面向全球中文开发者的技术内容分享与交流平台。我们通过技术文章、沸点、课程、直播等产品和服务，打造一个激发开发者创作灵感，激励开发者沉淀分享，陪伴开发者成长的综合类技术社区。