AWS Open Data Registry
The registry lists datasets that organisations have chosen to publish openly on Amazon's cloud, from Landsat satellite imagery to human genome references and large climate model outputs. Each entry links to the underlying storage location (usually an S3 bucket) along with usage examples and tooling.
Because the data already sits in AWS, the cheapest and fastest way to work with it is from inside the same cloud, where there is no transfer cost. You can stream files straight into an analysis job or copy them into your own bucket. Formats depend on the dataset and range from Parquet and CSV to domain-specific scientific formats.
Licences are set per dataset, so check the terms on each listing. For RAG, this is a strong source of large, cloud-ready scientific and geospatial corpora that would be slow to download but quick to process where they already live.
Related sources
AWS Data Exchange
A marketplace for finding, subscribing to, and using third-party data inside the AWS cloud. It carries both free open datasets and paid commercial data products, so you can pull licensed data straight into your AWS workflows without setting up separate transfers.
Datahub.io
A platform for publishing and finding open data packages: datasets bundled with consistent metadata in standardised formats. It hosts curated collections of widely used reference data, from country codes to exchange rates, ready to drop into a pipeline.
Google Dataset Search
A search engine for datasets that indexes millions of them from thousands of repositories worldwide. It does not host data itself: it points you to wherever each dataset lives, which makes it a fast first stop when you are hunting for a source on a specific topic.
Hugging Face Datasets
The largest open hub for machine learning datasets, with well over 100,000 datasets you can search, stream, and version. Many RAG-ready corpora live here, and its Python library lets you pull data straight into a pipeline in a few lines.