What you need
A running Navidrome server (0.50 or later works best, because it exposes the OpenSubsonic extensions RoadSonic uses for structured lyrics and richer metadata), a user account on it, and an iPhone on iOS 18 or later. For CarPlay you need a compatible car; for remote access you need your server reachable from the Internet over HTTPS.
You do not need a Navidrome administrator account. A regular user is enough — RoadSonic only reads the library, streams audio and reports plays and favorites back.
Expose Navidrome over HTTPS
RoadSonic refuses plain HTTP for remote addresses on purpose: your Subsonic token and every stream would otherwise cross the Internet in the clear. The usual setup is a reverse proxy — Caddy, Nginx Proxy Manager or Traefik — in front of Navidrome with a Let's Encrypt certificate. Caddy does it in two lines: `music.example.com { reverse_proxy navidrome:4533 }`.
If you only listen at home, you can skip this: RoadSonic accepts http://192.168.x.x or http://navidrome.local addresses once you enable “Allow unencrypted local HTTP” in Settings. Tailscale or WireGuard also work, since the address is then on a private network.
Connect RoadSonic
Open RoadSonic › Settings › Sources › Add a source › OpenSubsonic. Enter the full address including the scheme (https://music.example.com), then your Navidrome username and password. Do not append /rest or put credentials in the URL. RoadSonic authenticates with the Subsonic salted-token scheme, so the password itself never leaves the Keychain.
The first sync indexes every artist, album and track on the device. Navidrome pages albums by 500 and RoadSonic fetches tracks concurrently, so a library of a few thousand tracks is usually ready in under a minute; the index is then updated incrementally. Your 7-day trial starts at this moment.
Get the “Ready for the road” badge
Pick a reserve size in Settings › Audio cache: 20, 30 or 60 minutes. RoadSonic downloads complete tracks from your Radio, favorites and recently played until the reserve is full, verifies each file, and shows “Ready for the road” on the Listen screen. From then on, the reserve is refilled in the background while you listen.
For a long trip, download whole albums: open an album, tap Download. Downloads resume after a lost connection and are never evicted automatically. The cache budget (2, 5, 10 or 20 GB) is shared between the reserve, the current queue and your albums.
In the car
Plug the iPhone in (or connect wirelessly) and RoadSonic appears on the car screen with four tabs: Listen, Artists, Albums, Find. Playback started on the phone continues on CarPlay, and the CarPlay sound profile — equalizer, loudness normalization — is recalled automatically.
Siri works too: “Play my favorites”, “Start the radio”, “Play Radiohead”. Play reports go back to Navidrome, so Last.fm or ListenBrainz scrobbling configured on the server keeps working.
