NCBI hosts a large, open-sourced dataset of human SNPs (Single-nucleotide Polymorphisms). Further, they store a good deal of auxillary data that is related to each SNP. The data is hosted on an FTP server here:

ftp:https://ftp.ncbi.nlm.nih.gov/snp/.redesign/latest_release/JSON

and is split across 25 gzipped JSON files (Chromosomes 1-22, X, Y and Mitochondrial DNA), amassing a total compressed size of ~100GB (~2TB uncompressed!).

More details can be found in this series of blog posts, detailing a three-part walkthrough, breaking the development of this application down in three steps:

1. Downloading JSON SNP Data & Initilizing the Database
2. Extracting ClinVar Disease & Frequency Study Data
3. Efficiently Writing Data to PostgreSQL Database