There are various modules that can be used in Keras. These modules are as follows:

• Activations: In this module, there is a list of activator functions that are used to create Keras-based models. 
• Initializers: It provides a list of initializer functions that provides initial weight to different functions. 
• Regularizers: Regularizers are used in the optimization phase where it applies some penalties on layer parameters. 
• Optimizers: In this list, you will get a list of optimizers that are used to optimize the input weights.
• Callback: This module provides a callback function that can be used while training the model. 
• Losses: This function is used to find errors or deviations in the process of learning. The loss function is required at the time of the model compilation process.
• Image processing: Images can be converted into NumPy arrays with the help of this module. It is used in the data preparation phase.
• Text Processing: Text can be converted into NumPy arrays by using the Text Processing module. It is also used in the data preparation phase. 
• Sequence Processing: This module provides functions that are used to generate time-based data with a given input. 
• Utilities: Several utilities in deep learning are provided in this module. 
• Backend: It provides functions of backend libraries like Theano and TensorFlow.