What Is nsurlsessiond on Mac? Find and Pause the Transfer
When nsurlsessiond appears near the top of Activity Monitor, start by looking for a transfer that is still making progress. A photo upload, an app download and an unfinished sync need different controls, even when the busy process has the same name. Record what is happening before pausing anything.
What nsurlsessiond Does
nsurlsessiond is Apple's background transfer service. Apple's developer explanation identifies it as a system-wide service used for background URL sessions, rather than a separate app you installed.
That makes the process name a starting point, not the name of the app whose work you should stop. Check iCloud, Photos and download queues as candidates, without assuming that every transfer from those services uses this process.
For iCloud-specific troubleshooting, use the separate bird and cloudd guide. For broader attribution, see which app is using the network.
Separate Network Traffic From CPU Use
Open Activity Monitor and select Network. Apple's network activity guide distinguishes cumulative data sent and received from the per-second rates below the process list.
Compare the display at two points while the same transfer remains active. An already large total does not establish that the Mac is still transferring at a high rate.
| Observation | What to check next | What it does not prove |
|---|---|---|
| Received data keeps increasing | Active downloads and their progress | Which app requested a shared service's transfer |
| Sent data keeps increasing | Photo uploads and pending sync | That a particular library is responsible |
| CPU is high but traffic is low | Whether the source app reports progress or an error | That deleting a cache will fix it |
| Traffic falls after pausing one source | Resume that source and compare again | That no other transfer was active |
Treat CPU use as another observation to record, not a diagnosis of a corrupt library. The useful question is whether a visible job advances, finishes or repeatedly reports an error.
Check Photos and iCloud Before Changing Settings
In Photos, open Library, select All Photos, then scroll to the bottom. Apple's iCloud Photos instructions explain how to see the upload status and pause uploads for one day when that control is available.
Note the remaining work before pausing. If you recently added photos, compare the upload status with the network readings, rather than deleting photos to reduce traffic. The same Apple page explains that deleting a photo with iCloud Photos affects the other devices too.
For iCloud Drive, inspect the files you were waiting to sync before making a change. A file that you still need on another device is a reason to confirm its arrival, not a reason to switch off synchronization as an experiment. Keep an independent copy of anything irreplaceable.
Check App Downloads and Pending Updates
Open the App Store and look for a download in progress. Apple documents pausing and resuming an app download with the controls beside that download.
Also inspect Updates for the apps waiting to update, as described in Apple's manual update instructions. A pending update is something to investigate, not proof that it caused the traffic.
If you already started a macOS update, read its current progress before changing anything. Do not treat an installation phase as an ordinary app download or interrupt it merely to test a network theory.
Pause One Source and Check Again
Choose one visible transfer with a documented pause control, such as the Photos upload or an App Store download. Record the time, the progress shown and the network rate, then pause only that job.
Watch the same readings again. If traffic falls, resume the job when convenient and check whether progress and traffic return together. That supports the connection, but concurrent transfers mean it is not conclusive attribution.
If nothing changes, restore the first source before testing another. Do not stack changes to Photos, iCloud and updates, because you will no longer know which change mattered.
Killing nsurlsessiond is not the pause control used here. Apple's developer discussion links termination of the service to disconnected background sessions. Use the requesting app's controls and preserve its progress instead of turning a process restart into a repair routine.
When No Source Makes Progress
Keep a short record of the process name, time, CPU reading, network change and the exact error shown by the source app. Include whether pausing and resuming one job changed the result.
If the same app remains stuck, take that evidence to its support channel. If Photos is the source, include its sync status. Avoid deleting libraries, transfer databases or support folders while the owner of the work is still uncertain.
Where Mole Fits
Mole Mac's Status view shows total download and upload rates in its Network tile. Use those totals to compare before and after a source is paused, then return to the source app to manage its transfer.
A total rate is not evidence that nsurlsessiond belongs to Photos or any other particular app.
FAQ
Is nsurlsessiond an App I Should Uninstall?
No. It is Apple's background transfer service, so start with the app or service requesting the work rather than trying to remove the daemon.
Does High Network Use Mean Something Is Broken?
Not by itself. Compare a visible download or upload's progress with the current rate. A large cumulative total alone does not show a continuing problem.
Should I Force Quit nsurlsessiond to Stop a Download?
Use the source app's pause control where available. Change one job at a time, check the readings and resume it afterward, rather than interrupting a shared service.