OpenALPR is written in C++ and has bindings in C#, Python, Node.js, Go, and Java. Check out this guide for examples showing how to run OpenALPR in your application: http://doc.openalpr.com/bindings.html.

Here is the API for Python:

    from openalpr import Alpr

     alpr = Alpr("us", "/path/to/openalpr.conf", "/path/to/runtime_data")
     if not alpr.is_loaded():
         print("Error loading OpenALPR")
         sys.exit(1)

     alpr.set_top_n(20)
     alpr.set_default_region("md")

     results = alpr.recognize_file("/path/to/image.jpg")

     i = 0
     for plate in results['results']:
         i += 1
         print("Plate #%d" % i)
         print("   %12s %12s" % ("Plate", "Confidence"))
         for candidate in plate['candidates']:
             prefix = "-"
             if candidate['matches_template']:
                 prefix = "*"

             print("  %s %12s%12f" % (prefix, candidate['plate'], candidate['confidence']))

     # Call when completely done to release memory
     alpr.unload()