Useful Links
Access to the developer preview
You can get access to the Developer Preview here.
Official Website / UGC Hub
sbox.game is where UGC (User Generated Content) is hosted. This includes gamemodes, addons, models, maps, etc.
Official Documentation
The S&box Documentation site hosts documentation that is curated by Facepunch, rather than the community.
Discord
To ask for help, show off what you're working on, or just talk about S&box join the S&box Discord.
Bugs and Feature Requests
Do not post issues or feature requests for gamemodes, addons, or any other UGC even if under the Facepunch org.
If you have any issues or want to make a feature request for the editor or S&box overall, you can find the issues page here