spinics.net is mostly mailing list archives these days

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.

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

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。

canonical makes open source secure, reliable and easy to use, providing support for ubuntu and a portfolio of enterprise-grade technologies. founded in 2004, canonical operates globally with team members in over 80 countries.

面向企业提供一站式研发管理解决方案，包括代码管理、项目管理、文档协作、测试管理、cicd、效能度量等多个模块，支持saas、私有化等多种部署方式，帮助企业有序规划和管理研发过程，提升研发效率和质量。

an open source, standards-based software platform for multiple device categories, including smartphones, tablets, tvs, netbooks and automotive infotainment platforms.

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