CookieFirst is a consent management platform from the Netherlands. The banner is added either by loading a JavaScript file from their CDN or, if you already use Google Tag Manager, by placing their tag in the container. Appearance, texts and the list of services are configured in an admin panel.
The servers that visitors of the banner connect to are hosted in the EU, so consent traffic does not leave Europe. That makes CookieFirst a European alternative to American consent tools, and it suits sites of any size that have to document consent properly.