*All* sites that are not actual Q/A sites are not listed.

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- [SE Chat](https://chat.stackexchange.com)
- [SE Data Explorer](https://data.stackexchange.com)
- [Development Test site](https://dev.stackexchange.com)
- A few redirector sites
  - [Ask Ubuntu](https://ubuntu.stackexchange.com)
  - [MathOverflow](https://mathoverflow.stackexchange.com)

- [SO Blog](https://blog.stackoverflow.com) - This isn't really a sub-domain of stackexchange.com, but since SO is a part of the SEN, let it be here.
- [SO Blog (Alternative)](https://stackoverflow.blog) - Why two...

Strictly speaking, Area 51 is not *in* the list, but it's easily known and accessible (it's in the top-left dropdown menu of all sites, though).