In 1990 India had approximately 0% (upto 2 decimal places) of total population accessing internet. In 2010 this number has reached to 10% of total population. It means good internet infrastructure and excellent connectivity. But with internet availability there  comes one problem, high data usage bills. Let it be your PC, Android Phones, MACs or any other internet friendly devices; its pretty common to get high internet usage bills cause you dont know how much you have already used. Following are some of the tools you can use to keep yourself protected from high bills

Windows

• BitMeter 2 - http://download.cnet.com/BitMeter-2/3000-2381_4-10398686.html
• DU Meter - http://www.hageltech.com/dumeter/about
• Free Meter – http://sourceforge.net/projects/freemeter/
• NetMeter - http://www.softpedia.com/get/Network-Tools/Bandwidth-Tools/NetMeter.shtml
• Shaplus Bandwith Monitor - http://www.shaplus.com/bandwidth-meter/
• iiUsage : http://www.iiusage.com/
• Bandwidth Meter : http://www.bandwidth-meter.net/
• Net Speed Monitor : http://download.cnet.com/NetSpeedMonitor-32-bit/3000-2085_4-75592518.html
• Watch WAN: http://download.cnet.com/WatchWAN/3000-2381_4-10520334.html
• Traffic Usage Checker : http://www.tuc.co.nz/
• Networkx: http://www.softperfect.com/products/networx/
• NetTraffic: http://venea.net/?action=article&article=nettraffic
• tbbMeter - http://www.thinkbroadband.com/tbbmeter.html

Mac

• Surplus Meter - http://www.skoobysoft.com/utilities/utilities.html
• Menu Meter - http://www.macupdate.com/app/mac/10451/menumeters
• Net Use Monitor : http://www.netuseapp.com/

Linux

• nTop - http://www.ntop.org/

Android

• Onavo : http://www.onavo.com/
• Mobile Counter: https://play.google.com/store/apps/details?id=com.mobileCounter&hl=en

iOS

• Internal Data Usage Monitor – Go to your iOS Settings -> General -> Usage and go to “Cellular Usage”
• Data Usage Monitor  - https://itunes.apple.com/us/app/data-usage/id386950560?mt=8

 Some of the things you can do avoid high data usage

• Uninstall unwanted applications and software. Browse your phone, laptop and desktop all the junk software that you are not using
• Have a Good Antivirus Software on your PC. Here you can find a list of Free Antiviruses http://saurabhsays.com/free-antivirus-for-windows/
• Dont let applications run in background. For example facebook etc keep downloading and uploading data which might result in high bills.
• Be careful what you download. At times you end up downloading lot of data without actually knowing how much totally it adds upto.
• Avoid Video chat when you are on your 3G connection. Connect using Wifi.