Bandwidther

Bandwidther is a native macOS menu bar app for monitoring per-process network bandwidth in real time.

Note

This app was vibe coded using Claude Opus 4.6 and GPT-5.4. I do not have deep knowledge of macOS networking or SwiftUI such that I can confidently evaluate the end result.

Features

• Live per-process download and upload rates from nettop
• Sortable process list by rate, download, upload, total bytes, or name
• Menu bar popover with overall rates, cumulative totals, and a 60-sample sparkline
• Internet vs LAN/local connection summaries grouped by process
• Internet destination list with best-effort reverse DNS lookup
• Simple app visibility settings for Dock and Cmd-Tab app switcher presence

Requirements

• macOS 14+
• Xcode command line tools (xcode-select --install)

Install

Homebrew

brew tap btbytes/brew
brew install --cask bandwidther

Manual download

Download the latest release from the Releases page.

Build from source

This repo builds directly with the included Makefile; there is no Xcode project required.

git clone https://github.com/btbytes/bandwidther
cd bandwidther
make
open Bandwidther.app

Or build and launch in one step:

make run

How it works

Bandwidther uses built-in macOS command-line tools rather than packet capture or private APIs.

• Per-process bandwidth comes from nettop in delta mode. The app requests two samples and uses the second sample as the current per-process download and upload rate.
• The cumulative totals shown in the UI come from the baseline nettop sample. They are totals reported by nettop, not counters maintained independently by the app.
• Connection summaries come from lsof -n -P -iTCP -iUDP. The app parses socket entries, attributes them to processes, and classifies remote endpoints as internet or LAN/local using address heuristics.
• Reverse DNS uses getnameinfo, so hostnames are best effort and some destinations may remain as raw IP addresses.

Limitations

• The connection panels are socket snapshots, not packet-level accounting.
• LAN vs internet classification is heuristic. Private IPv4, loopback, link-local IPv6, unique-local IPv6, carrier-grade NAT space, and benchmark ranges are treated as local.
• The destination list currently focuses on internet destinations in the main UI.
• If nettop or lsof is unavailable or blocked by the system, Bandwidther may show incomplete data. nettop failures are surfaced in the UI.

Settings

Bandwidther includes a small Settings window with toggles for:

• showing the app in the Dock
• showing the app in the Cmd-Tab app switcher
• launching the app at login