Caliu is local-first: your notes live on your device, and the cloud is a backup, never a bottleneck. That shapes how sync works.
Local first, sync second
When you type, the change is saved to your device immediately. There is no save button and no spinner; the write is done before sync even starts. Syncing happens afterwards, in the background, whenever you have a connection.
Each device keeps its own queue
Every device maintains a queue of the changes you make on it. In the background, Caliu pushes that queue to the server in batches and pulls down whatever changed on your other devices. The server keeps a log of changes, so each device only fetches what it has not seen yet.
The web app syncs roughly every 20 seconds while you are working, and immediately when you return to the tab or come back online. The iPhone, iPad, and Mac apps sync in the background the same way.
Watching it happen
The sync indicator in the sidebar shows the current state: synced, changes pending, syncing, or offline. You never need to trigger a sync by hand.
If the same note is edited on two devices before either could sync, Caliu asks you which version to keep. See the article on conflicts.