BoingBoing: “Protomaps is a free and open-source map of the world for use in your websites, apps, and other projects: an alternative to hosted services, freer than Google Maps and simpler to adapt than OpenStreetMap.

• A fraction of the cost – Can reduce your mapping bills from hundreds per month to pennies, all on cloud infrastructure you use already.
• Take back control – Your map-based projects and sites don’t depend on a third party service or API keys, and work offline, forever.
• Hosted API – Protomaps also maintains a Tiles API – get a free API key. It’s free for non-commercial use, or commercial use paired with a GitHub sponsorship.”