Terms

Use it freely. It is given as it is, and the data belongs to OpenStreetMap's contributors rather than to me.

The game

Free to use, for anyone, including in a classroom. No account, no licence to accept, no attribution asked for. If a teacher wants to put it in front of thirty pupils, that is exactly what it is for.

The API

The public API is free and unauthenticated. There are no rate limits because there is no server to overload — it is static files behind a CDN. Two requests:

• Cache what you fetch rather than requesting the same file in a loop. The data changes a few times a year at most.
• If it becomes load-bearing for you, copy the files and serve them yourself. That is allowed, it is faster for you, and it means an outage here is not an outage there.

The API is versioned in its path. /api/v1/ will not change shape incompatibly; a breaking change becomes /api/v2/. That said, this is a free service run by one person and it comes with no availability promise of any kind.

The data licence, in plain terms

Boundaries and names derive from OpenStreetMap and are licensed under the Open Database License 1.0. What that means for you:

• If you display it — a map, an app, a graphic — credit “© OpenStreetMap contributors” where the people looking at it can see it. That is a Produced Work, and attribution is all that is required.
• If you redistribute the data itself, or a database you built from it, that database has to be offered under the ODbL as well, and you have to say what you changed.

In short: use the numbers, credit the mappers, and keep derived databases open.

The code

The site's source is MIT-licensed and on GitHub. Fork it, run your own copy, point it at another country if you like.

No warranty

City Memory is provided “as is”, without warranty of any kind. The boundaries are an OpenStreetMap extract, not a cadastral record: they can be out of date, simplified, or simply wrong, and they are simplified deliberately so the map draws quickly. Do not use them for anything where being wrong has consequences — legal, administrative, navigational or otherwise. To the extent the law allows, I am not liable for any loss arising from use of this site or its data.

Acceptable use

Do not attempt to break the site, and do not redistribute it in a way that implies it is yours or that it is official. Beyond that, there is nothing here to abuse.