(if I understood correctly,) any geojson will be close enough to the format you are looking for. For example:
I'm not sure where you are but for the UK you can download postcode to lat/long tables from a variety of sources.
UK postcodes to lat/long - this site also has a variety of other countries.
You then seem to be asking how to convert a csv into a list. Obviously for an app you don't want to have to load the csv every time as its a fairly expensive operation ...