what is the best tech to plot location ? both desktop and mobile platforms

I want to Dev an app which shows location

A map.

good one... but I need an application which invokes the map and plot what i want and when I want

Have you checked Google Maps? It has JS and Android APIs, as well as an iOS SDK.

Yes I did but Google do not have offline maps only online APIs

It does cache your location though.

see my requirement is not just one particular location I want entire country offline maps. for eg ESRI street maps which can be downloaded. say if I have to use this map in an application how to write this app and using what

Die you check openstreetmap?

What about Mapbox?

checking osm and can we build app on top of this ?

even OSM do not give me option to download for entire country

Downloading an entire country is probably a bad idea. But if you must, you're most likely going to have to license a map from someone. Tomtom comes to mind.

right but they are very expensive Tom Tom charges at least 500K usd for contry like UAE

That's because keeping map data up to date is expensive.

downloading OSM and can I use these APIs in Python ?

@Knochenbier did*