Here's basic information you need to know about testing.
Currently we do not offer sandbox version of our API. For the testing purposes, you just need to register in our app at app.foxentry.com.
After the registration you can freely create a new API project and you'll automatically receive testing credit worth 100 CZK and 14 day expiry date. It should be enough to properly test all the things you need.
Please let us know if you have special needs regarding the test project. We are used to the individual approach for our clients.