CKAN is open source data management portal software for extremely large data sets, on the scale of entire governments. Used to publish, curate, share, search, and find datasets of just about any kind. Does visualization and metrics. Source code on Github (https://github.com/ckan/ckan). Written in Python, uses Postgres as its back end. Can interface with Apache Solr for search and indexing.
An online catalogue of Victorian, Edwardian, vintage, and steampunk accoutrements, such as sextants, swords, compasses, and other nifty things.
A clone of Librarything. Used to inventory your personal library. Integrates Wikidata to get more information for the contents of your library.
API: https://api.inventaire.io/
Github: https://github.com/inventaire