What is nsurlsessiond on a Mac, and what is it downloading?
nsurlsessiond does background downloads and uploads for apps and macOS. High network use from it means a big transfer. How to see which app asked for it.
What is nsurlsessiond?
Apps hand transfers to nsurlsessiond so they can carry on in the background, even after the app quits: App Store and macOS updates, iCloud, podcasts, music and many third party apps. It lives at /usr/libexec/nsurlsessiond.
On our Mac two copies ran, one as the _nsurlsessiond system user and one as us, both at 0.0% CPU and 2 MB.
How do I see what it is downloading?
nettop -P -L 1 -J bytes_in,bytes_out | sort -t, -k2 -nr | headThat ranks processes by data received. If nsurlsessiond leads, check the App Store for updates, System Settings, General, Software Update, and any podcast or music app set to download. The app that asked is the one to change.
Can I stop nsurlsessiond?
Quitting it pauses transfers until it is started again. To stop the downloads themselves, turn off automatic updates in the App Store and Software Update, and automatic downloads in Music and Podcasts. Downloaded installers that pile up are covered in the Library Updates folder.
See it live
Free Mac's System tab ranks every process by processor use and energy impact, once a second, and marks the ones macOS will not let you quit as protected. See also which app is using the internet.
Common questions
What is nsurlsessiond on a Mac?
A macOS process that runs background downloads and uploads for apps and the system, such as updates and iCloud.
Why is nsurlsessiond using so much data?
An app or macOS asked it for a big transfer, often an update or a media download.
Can I disable nsurlsessiond?
Not safely. Turn off the automatic downloads that use it, or use Low Data Mode on metered networks.