Read the TOS: http://my.pinkfroot.com/main/authorization/termsOfService that governs the site
shipfinder.co (granted, the TOS was not easy to find):
to use any manual or automated means, including agents, robots,
scripts, or spiders, to access or manage any user's account or to
monitor or copy this Network or the content contained therein;
it is illegal to scrape the site and use the data for your own App.
Copying all or part of another website (or any other published work, be it a book, movie, music, article, internet resource, etc.) or the data from a site is illegal.
Is it legal to scrape a website and create my own database?
I have a question about copyright. What should I read before I ask it?
In our case, it's a free and open source mobile application.
The state of the end use of the data is irrelevant, whether open or closed source.
And the idea that "my app simulated a client on their web site" is OK in technical terms, just not in terms of copyright.