How does the CTC loss work? I am trying to implement CTC loss in Tensorflow, but their documentation is pretty limited. So I am not sure how to approach the problem. I found a good example in Theano: https://github.com/mohammadpz/CTC-Connectionist-Temporal-Classification/blob/master/ctc_cost.py.

Are any other resources that explain the CTC loss?

Also, I am trying to understand how its forward-backward algorithm works. And what is beam decoder in the case for CTC loss?
The paper Connectionist Temporal Classification: Labeling Unsegmented Sequence Data with Recurrent Neural Networks (2006), by Alex Graves et al., mentioned in the linked TensorFlow documentation, presents and explains the CTC loss and the CTC forward-backward algorithm (in section 4.1). 

Have also a look at this article Sequence Modeling With CTC (2017) by Awni Hannun.