Is there any way to transfer books that I own from Kindle, iBooks, etc. in to my Bookcrawler library?

Unfortunately, there isn't currently a way to grab the lists of books from any of these popular reading apps. The Apple iOS does not allow applications to inspect data from other applications for security reasons.  For bc to be able to examine data in another app, that app would need to provide an interface to allow bc to retrieve data.  I will be happy to implement this on my end as soon as another app does this.  I have tried to contact various apps to get this information, but so far no one has responded.  Perhaps if enough users contact the authors, one will be created.

The easiest way to proceed in the interim is to create a csv file and import all of the entries that way.  The format for the csv file can be found here:
CSV Documentation

 

The csv file is just a text file and can be created with any editor, but a spreadsheet application like Excel is the easiest way.  A simple list of titles and authors will work but you have the best shot at finding the correct match with an ISBN as well.  Once a csv import is done, you can load additional information under Settings -> Update Entries.

The other way to enter books rapidly is through the Authors interface.  You can add a new name, perform a search and then select multiple books at a time to enter them.