Core Concepts
A handful of terms come up throughout these docs. This page defines them once.
A hub is a single, independently-run instance of Citinet: its own database, its own file storage, its own set of members. Creating a hub gives you a small self-contained cloud for your community: notes, messages, files, a local marketplace, a map, and more, all documented in the User Guide.
A hub can run anywhere: a spare laptop, a home server, a small cloud VM. Whoever runs the hardware controls the hub.
The registry
Section titled “The registry”Hubs that want to be discoverable list themselves in a shared registry, so people can find hubs near them or search by name. Registering is optional: a hub set to “Local Network Only” never appears there at all, and stays reachable only to people already connected to it.
What’s centralized (and what isn’t)
Section titled “What’s centralized (and what isn’t)”Citinet follows one rule consistently: centralize only the on-ramp, decentralize everything downstream.
Concretely, a small set of shared services exist purely to make starting a hub easy:
- The hub-creation wizard and setup scripts
- The cert broker: issues each hub a real, browser-trusted HTTPS certificate automatically (see Automatic HTTPS and The Cert Broker)
- The optional public registry, for hubs that want to be discoverable
Everything a hub actually needs to run (its data, its members, its governance, its moderation decisions) lives entirely on that hub’s own hardware, under that hub’s own operator. If every one of Citinet’s shared services disappeared tomorrow, every already-running hub would keep working for the people already on it; only new-hub creation and public discovery would be affected.
This is a deliberate trade-off: a little bit of shared infrastructure in exchange for an onboarding experience that doesn’t require a hub operator to own a domain, understand DNS, or manage a certificate authority by hand.
Visibility
Section titled “Visibility”When creating a hub, an operator chooses how reachable it is:
- Local Network Only: reachable only by devices on the hub’s own network (plus, optionally, guests with no internet of their own; see Guest Wi-Fi Access). Never listed in the public registry.
- Tailscale: reachable from anywhere, via a private Tailscale network the operator controls.
Both get a real HTTPS certificate automatically; the difference is purely about who can reach the hub at all.