Surfroam

Surfroam charges by the kilobyte, which is unusual in the eSIM market where monthly bundles dominate. The service offers named tiers (ULTRA, PLUS, GLOBAL) with rollover mechanics built in, so your balance doesn't expire if you're not using data constantly. This works especially well for someone tethering a laptop or phone irregularly throughout a long stay abroad.

Operating since 2016, Surfroam appeals to travelers who want flexibility and hate wasting unused data. If you're taking a month-long trip but will only tether for a few hours per week, per-kilobyte billing means you pay for what you actually use instead of buying a fresh bundle every few days.