What is the best system/tool for tracking incoming leads?

[Ross Markey]

Hey BP Community! 

Can anyone recommend a good tool or system for tracking incoming leads? For example, when I find a potential property I want to put it into my "deal funnel" where I can work through my system for finding deals, and track where each property is within the system (i.e. showing scheduled, under contract, offer made, under contract by someone else - follow-up in X amount of time, and so on). 

Any good recommendations? Can be a free or paid service. 

Thanks in advance! 

Ross