Free and no ads…
https://play.google.com/store/apps/details?id=co.uk.happyapper.HereIamFree
You set up some locations that you are going to pass through when out on your bike/walk/commute/whatever. It then sends an SMS to whoever you’ve specified.
Just done as a way of learning how to write Android apps. My girlfriend likes to know I’m getting round a ride ok. I use it to tell her to put the kettle on when I’m about 10 minutes from home.
It works fine, but is a bit bare bones at the moment, future enhancements include…
1 sending emails/messages rather than SMS
2. altering the accuracy of the location spots, currently set at 25m, if you increased it you could use the app to automatically update someone of your location when driving.
3. a GPX overlay so it’s easy to set up locations on a ride you are planning
4. specify if you send a message as leave a location rather than when you enter it.
My first app, so be gentle,
Cheers.