Display a map with a pin on it by passing parameters in the URL

You'll find a lot of relevant information in this recent question.

Simple answer is https://www.openstreetmap.org/search?query= , but it has limitations.

Regards

You can search by address by appending search?query= to the URL, like this:

https://www.openstreetmap.org/search?query=221b%20Baker%20Street%20London

...but that won't show a marker on the map, at least until you hover the mouse over one of the Nominatum results.

You can add a marker to the map by specifying latitude and longitude with mlat and mlon parameters:

https://www.openstreetmap.org/?mlat=39.9155&mlon=4.1745

...but there's no way to do that with just an address.

However, if you're willing to do a two-step process, you can first query by address to get coordinates (you can use the Nominatum API directly, or just use the search?query= method and pull the top result's coordiates from the redirected URL after the #map= string) and then construct a marker URL with the mlat and mlon parameters.