UniFi OS 4.x introduced a content filtering feature (Cybersecure menu) that supports custom domain block lists per network. The API endpoint is not officially documented but works with the standard API key.
- UniFi OS 4.x (tested on UniFi Express 7, firmware 4.4.x)
- API key with network access (
Settings → Control Plane → API Keys) - The content filter profile ID (see below)