What is WiFi Scanner?
A 802.11 wireless scanner and connection manager for Mac OS X. WiFi Scanner will detect access points and clients in ad-hoc mode if the SSID is being broadcasted. It can be used for wireless site surveys, wireless discovery, and to connect to WiFi networks. The tool reports signal strength in dBm and shows access point BSSID/MAC addresses.
Change Column Positions Sort Results Resolve Vendor OUI Noise and Signal/Noise Info Autoscan/Refresh Access Point Finder Using Audio Alert Integration with Sensor Pro as a remote GPS device
WiFi Scanner Screenshots
WiFi Scanner Features
WiFi Scanner information
Comments and Reviews
Said about WiFi Scanner as an alternative
Another good (commercial/paid) alternative to InSSIDer. This too (similar to WiFi Explorer) shows list of WiFi sources and graphs of signal strengths. Also lists connected devices.