What is nsurlsessiond on a Mac, and why is it downloading?

27 October 2026 · 5 min read

nsurlsessiond is the macOS process that downloads and uploads data in the background for apps and for the system. When an app asks macOS to fetch a file, such as an update, a podcast episode or a media library item, nsurlsessiond often does the transfer so it can carry on in the background. If it is using your network, some app or macOS feature asked it to, and it will stop by itself when the transfer is done.

It is a normal part of macOS. You cannot uninstall it and you do not need to. What you want to know is who asked it to download, and whether the transfer is something you want.

What the name means

The name comes from NSURLSession, the macOS and iOS programming interface apps use to load things from the internet. Apps can use it in the foreground, where they handle the download themselves, or hand a transfer to the system. When they hand it over, nsurlsessiond is the process that carries it out.

The reason is practical. An app that starts a large download should not have to stay in front and busy for the whole thing. By giving the job to nsurlsessiond, the app can get on with other work, or even quit, and the result is handed back when the transfer finishes. The same system lets macOS hold a transfer until conditions suit it, and pick up one that was interrupted.

So there is no single thing nsurlsessiond downloads. It downloads whatever apps and macOS ask it to.

What it is usually fetching

Without looking at a specific Mac I cannot say what it is downloading on yours, but the common sources fit a pattern. They are things you would expect to arrive while you were not watching.

App and system updates. Apps that update themselves, and some Apple features, use background transfers to fetch the new version.
Media and content libraries. Podcast episodes, TV and music downloads, and similar items in Apple apps arrive this way when you ask for them or when an automatic download is on.
Content from apps you have installed. Any app that downloads big files, such as maps, documents, game assets or a cloud folder, may hand the transfer to the system.
Uploads. It handles uploads too. An app that backs up or shares a large file can send it in the background.

macOS also has processes for specific jobs, such as softwareupdated for macOS updates and storedownloadd for App Store downloads. nsurlsessiond is the general-purpose one.

You may also find two copies of it. macOS runs one for the system, under a system account, and one for your own login. Both do the same kind of work: the system one for macOS services, yours for your apps.

Why it can look like it never stops

A few things make nsurlsessiond seem busy all the time.

Automatic downloads. If you have turned on automatic downloads for an app, new items arrive whenever they are published, so it will be active from time to time.

A transfer that keeps retrying. If a server is slow or a connection drops, the transfer restarts. You will see network use come and go instead of finishing.

Many apps at once. After you start the Mac or join a different Wi-Fi network, several apps may begin the transfers they had put off. Why your Mac is slow right after you start it up covers that pile-up.

A queue after being offline. If your Mac was asleep or off the network for a while, the apps’ waiting transfers all start when the connection comes back.

How to find out which app asked for it

nsurlsessiond works for others, so the useful question is who. There is no single screen in macOS that lists that neatly, but you can narrow it down.

Think about what changed recently. Did you install an app, turn on automatic downloads, or open a media app? The timing often points to the cause.
Open each likely app and look for a downloads or activity area. Apps that download large things nearly always show progress somewhere.
Check System Settings under General, then Software Update, to see whether a macOS update is downloading, and the App Store app’s Updates list for app updates.
Try quitting the apps you suspect, one at a time, and watch whether the network use stops. A transfer handed to the system can keep going for a while after its app has quit, so if nothing changes, reopen the likely app and look at its downloads.
If you use Terminal, pgrep -l nsurlsessiond lists the copies that are running, usually two. That they exist is not the clue, since they are nearly always there. What matters is how much they move.

Be careful not to blame the process. A burst of network use from nsurlsessiond is rarely a security problem. It is a sign that something you or macOS asked for is arriving.

Should you stop it?

You should not end it. If you do, macOS starts it again, and any transfer in progress is cut off and may have to begin again. The right fix is at the source:

Pause or cancel the download inside the app that started it.
Turn off automatic downloads in the app if you do not want them.
If the problem is your connection, hold off on large transfers until you are on a faster network.
If you are on a metered network such as a phone hotspot, check the app’s settings for a way to download only on Wi-Fi.

If network use stays high and you cannot find a reason, restart the Mac and see whether it comes back. A restart can clear a transfer that is stuck retrying.

Seeing it in Foreman

Foreman shows nsurlsessiond with the plain name “Background downloads” and a line that says it downloads and uploads data in the background for apps and macOS, with the real name in grey beside it. Your copy sits under Background processes and the system’s under System processes. The Network column on the Processes page shows how much each is moving right now, sorting by Network puts the busiest at the top, and the network graph on the Performance page shows the whole Mac’s traffic. That gives you the “is it really downloading” answer in one look, instead of guessing from a fan or a slow web page.

Foreman does not show you which app asked for the transfer, and it will not block network use. What it gives you is the size of the problem, so you can decide whether to wait. If you want to go deeper into what is using the processor at the same time, how to find out what’s running in the background on your Mac walks through the full list.

The short version

nsurlsessiond does background downloads and uploads for apps and macOS.
It is normal, nearly always running, and idle most of the time.
Heavy network use means an app or update asked for a large transfer.
Find the app that asked, and pause or turn off the download there.
Do not end it. macOS restarts it and the transfer may start over.

If you would rather see the transfer than guess at it, Foreman is free for 24 hours, then $12 once.