Simply copy in a column of coordinates matching one of the three formats, click the relevent button and the other boxes will be occupied by the converted coordinates. Limited to 500 points.
i.e O 21112 21112
i.e 321112, 221112
i.e 321112 221112
i.e 53.2269, -6.1872
While working on a Python GIS application, I stumbled across 'the age old problem of bulk conversion of Irish Grid References to GPS coordinates'.
It struck me odd that there wasn't an online resource for converting.......so I built one.