Keepgo

Keepgo has been selling international data since roughly 2011, long enough that its core idea, a balance that never technically expires, has become the thing it's known for. Instead of a plan that runs out after 30 days whether you used it or not, Keepgo's leftover data carries forward indefinitely provided you add at least a small top-up (around €3) once every year, which suits people who travel a few times annually and hate re-buying data they never touched.

Coverage comes in regional bundles rather than country-by-country plans, with the Global tier covering about 102 destinations and smaller regional packs, like Europe, covering 30-plus. Pricing starts near €2 for 100MB and scales up to bundles over 100GB, all data-only with no voice or text included. Refunds are available within 30 days on an eSIM you haven't installed, minus a 10% fee, but once it's active the balance is yours to use or bank. It's a solid fit for occasional long-haul travelers and repeat visitors to the same region who'd rather carry data forward than lose it every month.