inSSIDer

Get the best open-source Wi-Fi scanning software – for Free!

see full-size screenshot below
YOU CAN
– Inspect your Wi-Fi and surrounding networks
– Scan and filter hundreds of nearby access points
– Troubleshoot competing access points and clogged Wi-Fi channels
– Highlight access points for areas with high Wi-Fi concentration
– Track the strength of received signals in dBm over time
– Sort results by MAC Address, SSID, Channel, RSSI, Time Last Seen
– Export Wi-Fi and GPS data to a KML file in Google Earth
TECHNICAL
– Uses your current wireless card and connection software
– Works with Windows XP, Vista, and 7 (32 and 64 bit)
– Compatible with most GPS devices (NMEA v2.3 +)

version 2.1 update:
Improves Filters
- Include or Exclude SSID or Vendor
- Channels
- Network
- Security
Improves Design
- Active network is now bolded
- Improved color pallet