TrafficMonitor - TrafficMonitor is a network monitoring suspension window software in Windows.
Surge for Mac - Advanced Web Debugging Proxy for Mac & iOS
NetBalancer - NetBalancer is a Windows application for local network traffic control and monitoring.
Charles Proxy - HTTP proxy / HTTP monitor / Reverse Proxy
FreeMeter - Monitor network bandwidth (C#.NET 2k/XP+). Desktop and Systray graph.
HTTP Toolkit - Beautiful, cross-platform & open-source tools to debug, test & build with HTTP(S). One-click setup for browsers, servers, Android, CLI tools, scripts and more.