Openstreetmap | Create A Visually Stunning Heapmap (1,200 plots)

Requirements: Create a visually studding heatmap using Openstreetmap. I will supply you with 1,200 longitude and latitude values, which will need to be placed on the map and returned like the attached example ([login to view URL]). The attached example was from a free online tool, which is no longer available - I want the same aesthetic as per the attached. Please I believe they used 'OpenStreetMap' from Google in the background - but not necessary. I have also played around with QGIS, which actually has the same result as needed - but unsure how to upload a file myself.