Data.gov
US government open data portal
Data.gov is the US government's open data portal. It catalogs datasets from federal agencies and links to their sources, and it offers a catalog API.
More in Data marketplaces
AWS Data Exchange
Data marketplaces
Marketplace for third-party datasets on AWS
Databricks Marketplace
Data marketplaces
Open marketplace built on Delta Sharing
Datarade
Data marketplaces
Directory to compare and request data products
Hugging Face Datasets
Data marketplaces
Datasets hub for machine learning
Kaggle Datasets
Data marketplaces
Public datasets shared by the community
Nasdaq Data Link
Data marketplaces
Financial and alternative datasets, formerly Quandl