City, Gdańsk vs Colorado Information Marketplace

Otwarty Gdańsk (Open Gdańsk) runs a standard CKAN 2.x installation; a live keyless GET against `ckan.multimediagdansk.pl/api/3/action/package_search` returned full JSON dataset metadata with a wildcard `Access-Control-Allow-Origin` header on both the plain response and an OPTIONS preflight. The catalogue covers Gdańsk municipal transit, budget, and environmental datasets, with individual resources downloadable as CSV, JSON, or XLSX depending on the publisher.

The Colorado Information Marketplace is the state's open-data portal, built on the Socrata platform and covering budget, transportation, public-safety, and demographic datasets from Colorado agencies. Every dataset is queryable through Socrata's SODA REST API without an account, with an optional free app token only needed to raise the anonymous rate limit. Results are returned as JSON by default, with CSV and XML also available per dataset.