If you are trying to build Machine Learning/AI applications, you may need a lot data to test your models. Here are a few of my favorite lists and a search engine for finding data sets.
- Kdnuggets Datasets for Data Mining and Data Science
- Google Dataset Search is another cool resource. I discovered it while browsing through the KDnuggets page.
- Awesome Public Datasets repository is a GitHub repository of resources. Check out many other data sets on GitHub.