NetStumbler is a tool for Windows that allows you to detect Wireless Local Area Networks (WLANs) using 802.11b, 802.11a and 802.11g. It has many uses:

- Verify that your network is set up the way you intended.
- Find locations with poor coverage in your WLAN.
- Detect other networks that might be causing interference with your network.
- Detect unauthorized "rogue" access points in your workplace.
- Help aim directional antennas for long-haul WLAN links.
Use it recreationally for WarDriving.