General data collections
KDnuggets: https://www.kdnuggets.com/datasets/index.html
Anylytics: https://www.analyticsvidhya.com/blog/2016/11/25-websites-to-find-datasets-for-data-science-projects/
UCI: https://archive.ics.uci.edu/ml/datasets.html
some projects: https://www.dataquest.io/blog/free-datasets-for-projects/
Classified data sets: https://github.com/awesomedata/awesome-public-datasets#finance
Another list: https://www.datasciencecentral.com/profiles/blogs/big-data-sets-available-for-free
More collections: https://dreamtolearn.com/ryan/1001_datasets
Another one: https://www.forbes.com/sites/bernardmarr/2016/02/12/big-data-35-brilliant-and-free-data-sources-for-2016/#3df3c56db54d
more: http://bigdata-madesimple.com/70-websites-to-get-large-data-repositories-for-free/
Data.gov: https://catalog.data.gov/dataset/north-american-industry-classification-system-naics
Financial data:
19 free datasets: https://www.springboard.com/blog/free-public-data-sets-data-science-project/