This is an Acceptable Use Policy for the server running at nominatim.openstreetmap.org and does not apply to nominatim services run by yourself or other organisations
OSM’s Nominatim service is mainly there to power the search bar on openstreetmap.org. We are in principle happy for the public API to be used by external users for creative and unexpected uses. However, be aware that the service runs on donated servers and has a very limited capacity. We therefore ask you to limit your use and adhere to this usage policy.
Use that is directly triggered by the end-user (for example, user searches for something) is ok, provided that your number of users is moderate. Note that the usage limits above apply per website/application: the sum of traffic by all your users should not exceed the limits.
Apps must make sure that they can switch the service at our request at any time (in particular, switching should be possible without requiring a software update). If at all possible, set up a proxy and also enable caching of requests.
Note: periodic requests from apps are considered bulk geocoding and as such are strongly discouraged. It may be okay if your app has very few users and applies appropriate caching of results. Make sure you stay well below the API usage limits.
As a general rule, bulk geocoding of larger amounts of data is not encouraged. If you have regular geocoding tasks, please, look into alternatives below. Smaller one-time bulk tasks may be permissible, if these additional rules are followed
The following uses are strictly forbidden and will get you banned:
Please be aware that this usage policy may change without notice. In particular, the definition of heavy use may need to be modified in the future and you might have your access withdrawn. Commercial applications should keep that in mind when relying on this API for serving paying customers.
For slightly larger requirements you may be able to use commercial third-party providers. Some are listed on the Nominatim wiki page.
If your requirements are even larger you can install your own instance of Nominatim.