Best apps for keeping track of booked tour dates for freelance tour guides?

Any suggestions or recommendation for a SIMPLE, easy to use app/software to keep track of what tours I am doing, for whom, for how long, when? I am looking for a schedule planner with an overview and the ability to go into more details. Is there one specifically designed for Freelance Tour guides?

Hi there Christel, I'm Larry from The Travel Planner (www.thetravelplanner.com.au). I have an excellent product that I can easily add freelance functionality to it. I don't charge for this work as I feel that it's helping the travel community. I only ask that you take out a yearly ( not per month!) subscription for $36 AUD /year. Let me know if you're interested. Hello@thetravelplanner.com.au.
Best regards
L