Show Per-Process Network Usage with nettop
Monitor which processes are sending and receiving data, live, with the built-in nettop.
Run `nettop -P -l 1` to print one sample of network traffic per process, with totals.
01Command
Command
$ nettop -P -l 102What it does
When the fan spins up or data disappears on a capped plan, nettop attributes traffic to individual processes — something Activity Monitor's Network tab makes hard to compare. -P aggregates per process, and -l 1 gives a single snapshot; run plain `nettop -P` for the live animated view. The bytes_in/bytes_out columns show cumulative traffic since the process started.
03Risk
!Warning: Counts are cumulative since launch, so a long-running process shows large totals even while idle — sample twice and compare the deltas for the current rate.
04Undo
✓No undo needed — this command does not change persistent state.
05Sources
- nettop(1) — display network activity by processEvidence: Documents nettop -P aggregating traffic per process and -l 1 taking a single sample instead of an animated display.
Last verified: 2026-09-18 · Category: Developer