Machine Learning models are increasingly being adopted in many applications. The quality of these models critically depends on the input data on which they are trained, and by augmenting their input data with external data, we have the opportunity to create better models. However, the massive number of datasets available on the Web makes it challenging to find data suitable for augmentation. In this demo, we present our ongoing efforts to develop a dataset search engine tailored for data augmentation. Our prototype, named Auctus, automatically discovers datasets on the Web and, different from existing dataset search engines, infers consistent metadata for indexing and supports join and union search queries. Auctus is already being used in a real deployment environment to improve the performance of ML models. The demonstration will include various real-world data augmentation examples and visitors will be able to interact with the system.