I'm in need of a plug and play text recognition system after having tried some solutions such as Tesseract OCR, Google's Vision API seemed to produce the best results for me.
However I have never used any of their cloud API before but I've noticed it is able to work offline? How would billing work for this? As I understand the online version charges for every 1000 images, wouldn't the offline library circumvent this? What is the quality difference between online and offline?
Both online and offline charge based on the features used. Here is the pricing chart: https://cloud.google.com/vision/pricing
Quality should be similar for online and offline. You could run a small experiment with your own files to verify this.