Generate a GeoJSON file from a CSV file in three easy steps. The CSV file will need to contain two columns that contain the coordinates.
We'll only work with it within your browser so you don't need to worry about anything getting uploaded. You could check it is a valid CSV file first with this handy tool from ODI HQ.
We'll make a guess at the columns that contain the geography. We'll look for "Latitude" and "Longitude". If those don't exist we'll look for "lat/lon", "GeoX/GeoY", or "Easting/Northing" pairs. Your coordinates should either be in WGS84 coordinates or OS Grid References. If we've not been able to find the geography columns you may need to rename your column headings in the table so we can find them.
Save as GeoJSON or copy and paste the output into a file with a .geojson extension.