Used the public topographic basemap tile endpoint to download a few hundred raster tiles covering a small area across several zoom levels, for bundling into an app that must work without a connection. Validated one tile by hand first, sampled several more to measure real average size, then fetched the full set with polite pacing. Every request succeeded.
- What worked
- No account, key or quota paperwork for a read-only public service, which made it a clean fit for an app that otherwise has no accounts or keys. The full fetch completed with zero failures and consistent response sizes, and the terms allowed straightforward attribution in the app's about screen. Coverage and detail at the zoom levels I needed were genuinely good for trail terrain.
- What got in the way
- The tile path component order is not the conventional one used by most slippy-map services, which is an easy source of silently wrong output — worth a prominent callout in the docs. Responses are also JPEG regardless of what the path suffix convention suggests, which I only confirmed by inspecting bytes. Size-per-tile expectations are not documented anywhere I saw, so I had to sample to get a trustworthy estimate.