macOS process library
What is nsurlsessiond on Mac?
nsurlsessiond is a per-user daemon that carries out background downloads and uploads for apps. An app hands a transfer to macOS, and nsurlsessiond performs it in a separate process, so it can keep going while the app is suspended or closed.
- Part of
- macOS networking, working on behalf of apps that use background transfers.
- Safe?
- Yes. It is part of macOS.
- Can I quit it?
- You can, but macOS starts it again and the apps’ pending transfers carry on later.
The short answer
When nsurlsessiond is busy, some app is moving data in the background: syncing, downloading updates, or fetching media. The transfer itself is the work. Find the app that asked for it and pause or adjust that app.
Normal use
What nsurlsessiond usually looks like.
Usually it sits near zero CPU with a small amount of memory. You may see two copies in Activity Monitor, which is normal.
During big transfers its numbers in Activity Monitor’s Network tab climb much more than its CPU. Apps can mark transfers as time-insensitive so macOS waits for good conditions, like being plugged in or on Wi-Fi, which is why it sometimes gets busy when you connect your charger.
Why nsurlsessiond uses so much CPU or memory
- Large downloads
App updates, offline media, and other big files that apps queue for background download all run through nsurlsessiond.
- Cloud and media sync
Apps that sync files or media in the background often hand the transfers to macOS.
- Deferred transfers starting at once
Transfers waiting for power or Wi-Fi can all start together when you plug in or join a network.
- A transfer that keeps failing
A download that fails and retries can keep nsurlsessiond busy without ever finishing.
How to calm nsurlsessiond down
Start at the top. Each step is more disruptive than the one before.
- Check the Network tab
In Activity Monitor, open the Network tab and sort by bytes received or sent to see how much it’s moving.
- Let it finish
Most background transfers end on their own. Staying on a fast network helps them finish sooner.
- Pause sync in the app
If a sync or media app started the transfer, pause it or quit that app.
- Limit background apps
In System Settings → General → Login Items & Extensions, turn off Allow in the Background for apps that don’t need to transfer data while closed.
- Restart
If it keeps retrying the same transfer, a restart clears it.
Seeing it in Spare
Find what it’s reacting to.
nsurlsessiond works for apps, so the question is which one. Spare groups each app with its helper processes and shows what was running at the same time, which narrows down the likely source.
Spare doesn’t monitor network traffic, so use Activity Monitor’s Network tab to see how much data is moving. Spare treats nsurlsessiond as a system task and never offers to stop it.
Common questions
About nsurlsessiond
Is nsurlsessiond a virus?
No. It is part of macOS and performs background transfers for apps.
Why is nsurlsessiond using so much data?
It’s downloading or uploading something an app asked for. The data belongs to that app’s download or sync, not to nsurlsessiond itself.
Can I disable nsurlsessiond?
No, and you don’t need to. Pause or limit the app that’s asking for the transfers instead.
Why are there two nsurlsessiond processes?
It runs per user, and macOS often has a separate copy for system tasks. Two copies is normal.
Related processes
Sources: Apple: Downloading files in the background, Apple: Open items automatically when you log in. Reviewed October 6, 2026.
Get Spare
Free to use. Yours to explore.
Download Spare for Apple silicon, or explore the MIT-licensed source on GitHub. Free to use, with no subscription or account.
macOS 14+ · Apple silicon · Signed and notarized