I am looking for an international data sim card
Such a thing does not exist.
Once you are outside of your home turf, you are in roaming territory.
Your best bet is to :
•Shop around your home country for the provider with the best bundled roaming deals (e.g in the UK 'Feel at Home' from Three, or 'EuroTraveller' from Vodafone). Switch your primary contract to that provider (or activate the bundle if you are already with them).
• For the locations you visit on a regular basis where the roaming falls outside of the aforementioned bundled package, buy a PAYG SIM card in a local shop in the destination country and top that up a little bit each time you visit in order to keep it active. Upon arrival in said country, swap your SIM.
• There are other options out there such as Truphone ... but they are more business type solutions with the associated price tag, so for the average punter such as yourself, the old SIM-swap game is likely to be the way forward.