Sync and cloud storage

What is cloudd?

cloudd is the macOS daemon behind CloudKit. Apps that keep their data in iCloud sync it through cloudd, so the traffic shows under cloudd and not under each app.

Process: clouddMade by AppleApplies to: macOS 14 Sonoma and later. The Saved to iCloud list is in macOS 15 Sequoia and later; in macOS 14 it is Apps Using iCloud. Checked on macOS 27.2.Checked: 1 November 2026

Short answer

Part of macOS. It syncs the iCloud data of apps that use CloudKit, so its traffic belongs to those apps.

Don’t block

Don't block it. iCloud sync for many apps stops, and Apple says that macOS security data also comes through CloudKit.

Path
/System/Library/PrivateFrameworks/CloudKitDaemon.framework/Support/cloudd
launchd label
com.apple.cloudd
Signing identifier
com.apple.cloudd

What it is

The man page calls cloudd “the system daemon backing the CloudKit feature”. It is in the CloudKitDaemon framework of macOS.

CloudKit lets apps store data in iCloud containers. Apple's own apps use it, and other apps can too. The traffic goes through cloudd, not through each app.

launchd starts it as com.apple.cloudd, both for each user and for the system. It runs only while there is CloudKit work to do.

Why it uses the network

  • Sync of app data. When you change data in an app that uses iCloud, cloudd uploads the change. It also downloads changes made on your other devices.
  • A first sync. After you sign in to iCloud, or turn on iCloud for an app, all of that app's data can sync at once.
  • CloudKit content for macOS. Apple's host list says that CloudKit content includes XProtect updates and Voice Control assets. Apple Platform Security says that notarization updates are distributed using CloudKit sync.

How much is normal

Short bursts after you change something in an app are usual. The size depends on what changed.

A first sync after you sign in, or after you turn on an app, can be large. It depends only on how much data that app keeps in iCloud.

Long, steady uploads mean that one app syncs a lot of data. Find the app in the iCloud settings.

When it uses a lot, and why

  • A new Mac or a new sign-in. Every app that uses iCloud downloads its data. This happens once, and it can take a while on a large account.
  • An app with a lot of data in iCloud. When such an app imports or changes many items at once, every change syncs. Large attachments make it bigger.
  • You turn on iCloud for an app. Apple says that the app's information is then stored in iCloud and kept in sync. Everything that app already has on the Mac goes up.

Is it safe to block?

Don’t block

Don't block it. iCloud sync for many apps stops, and Apple says that macOS security data also comes through CloudKit.

What breaks if you block it

  • Apps that keep data in iCloud stop syncing with your other devices. Changes stay on this Mac until you allow it again.
  • Shared notes, reminders and other shared iCloud data stop updating.
  • CloudKit content that macOS needs, such as XProtect updates, can't download.

Blocking means a firewall rule that refuses its connections. Don’t quit or disable a macOS process to save data: macOS starts it again, and other features depend on it.

Reduce its use

  1. Choose Apple menu › System Settings. Click your name, then click iCloud.

  2. Under Saved to iCloud, click See All. Turn off the apps that you don't need to sync on this Mac.

  3. Apple says that an app with iCloud off no longer connects with iCloud. Its data then exists only on this Mac.

  4. On a hotspot or a capped plan, turn on Low Data Mode. Choose Apple menu › System Settings › Wi-Fi. Click Details next to the network, then turn on Low Data Mode.

  5. Don't quit cloudd in Activity Monitor. macOS starts it again, and many apps depend on it.

See how much it uses

  1. Open Activity Monitor from Applications › Utilities. Click Network.

  2. Type cloudd in the search field. The Sent Bytes and Rcvd Bytes columns show what it moved since it started.

  3. In Terminal, watch only this process. Press d to show the change per second, and q to quit.

    nettop -p 'cloudd' -P

With Kilobat

  1. In the Kilobat app list, search for cloudd. Its row shows the live rate and what it moved today.

  2. In Connections, click the ⓘ button on one of its rows. The popover shows this page’s short answer, without going online.

  3. In Terminal, ask the same question. Add --json for scripts and agents.

    kilobat explain 'cloudd'

  4. Show its traffic over one day.

    kilobat bandwidth 'cloudd' day

  5. Through MCP, an AI agent asks explain_connection with the process name. It gets the same facts.

The live view and the explanations are free. History in the app needs Kilobat Pro. Blocking needs Pro and the network filter: see the network filter, Protection and the hotspot data saver.

Hosts it contacts

Apple and the maker document these hosts for this feature. A process can also contact others; Kilobat’s Connections tab shows what it actually opens on your Mac.

*.apple-cloudkit.comApple's CloudKit service. Apps sync their iCloud data through it, and Apple lists api.apple-cloudkit.com for app notarization on macOS.Apple →gateway.icloud.comApple's CloudKit gateway. Apple lists it for CloudKit content, including XProtect malware definitions and Voice Control assets.Apple →*.icloud.comApple's iCloud domain. Apple lists *.icloud.com for iCloud services; specific hosts under it have their own pages.Apple →*.apple-dns.netApple's domain for the DNS of iCloud services. iCloud hosts resolve through names under it.Apple →*.cdn-apple.comAn Apple content delivery domain. Apple lists it for iCloud services; update and sign-in hosts sit under it too.Apple →

Questions

Is cloudd the same as iCloud Drive?

No. iCloud Drive files sync through bird. cloudd syncs the data of apps that use CloudKit.

Can I see which app cloudd syncs for?

Activity Monitor shows only cloudd. With its network filter on, Kilobat names the app that a connection was for.

Is cloudd a virus?

No. It is part of macOS, signed by Apple, and it has a man page. Open it with man cloudd.

Sources

Checked on 1 November 2026.