I don't know how to use google map API, is that free? If have any example could you please share with me?
Or I have any non-google API solution, don't hesitate to let me know as well, thank you in advance!
Attached is a quick example file that gets the directions, but doesn't extract the travel time
Are you wanting drive time, or just the direct distance?
The google map API is free only up to a certain number of transactions per year, which is quite low.
Here Maps API has a 'freemium' account allowing for a number of free transactions per month.
Just drive time.
There is no free API that I know of.
Perhaps OpenStreetMap has one, if they have good enough coverage for the area you want.
If use google map API, my API request demand not too much, maybe maximum 20 times one day, is that free as per google map API policy?
That might not be within the free limits.
I just edited my answer above because the HERE maps API resets the free usage each month also, so you could try either platform. You could even use both "free" API amounts to keep your solution free. The good thing is adding the functionality that you want is really easy in FileMaker!
The Google and HERE maps API's have a simple REST API, you will get the answer in JSON and can use the JSON functions in FileMaker to get the "Travel Time"
Use the "Insert from URL" script step with the rest api
Get Started | Directions API | Google Developers
Car route from A to B - Routing API - HERE Developer
Retrieving data ...