For a French traveler planning to go abroad, the choice of using an eSIM depends largely on the destination. Within the European Economic Area (EEA), the "Roam Like at Home" policy allows French users to use their mobile data, calls, and SMS without extra charges, except in the United Kingdom, which is no longer part of the EEA due to Brexit. Outside the EEA, eSIMs become more useful, especially in countries like the United States, Canada, Morocco, Tunisia, Turkey, Japan, and Thailand, where mobile data can be costly without a local plan. An eSIM offers a convenient alternative to buying a physical SIM card on arrival or using an international data pass from a French provider. It allows travelers to keep their French phone number while using a second line for mobile data, which can be especially useful for managing calls and messages separately from data usage. The choice of eSIM depends on the destination, data needs, and whether the traveler's phone supports eSIM technology, which is now common in newer models from Apple, Samsung, and Google. Several eSIM providers were evaluated as of September 3, 2026, with prices converted to euros using an exchange rate of approximately 1 dollar to 0.861 euro. Ubigi offers a 10 GB/30 days plan for 14 € in the U.S. and 16.50 € in Japan, while Airalo provides similar data volumes at slightly higher prices. GoMoWorld stands out with larger data volumes at lower prices, such as 9 GB for 30 days in the U.S. for 10.99 € and 14 GB for 30 days in Japan for 10.99 €. Saily offers prices close to Airalo but includes additional security features, and Holafly provides unlimited data plans, though at significantly higher costs—68.90 € for 30 days in both the U.S. and Japan. Before purchasing an eSIM, travelers should check if their French mobile plan already includes enough data for their destination. The "Roam Like at Home" policy covers the European Union, Iceland, Liechtenstein, Norway, Ukraine, and Moldova. For other destinations, an eSIM may be more cost-effective than an international pass from a French operator. Once the eSIM is purchased, it can be activated via a QR code or the provider’s app, allowing the French line to stay active for calls and SMS while the eSIM manages data usage. The amount of data needed depends on the length of the trip and how much mobile data the traveler expects to use. A 5 GB plan might be sufficient for a short stay with regular Wi-Fi access, while 10 GB offers more flexibility. Unlimited data plans are suitable for heavy users but may slow down after a certain usage threshold. Local eSIMs are often more cost-effective than global or regional plans for specific countries. The best eSIM depends not just on data volume but also on coverage, price, and compatibility with the traveler’s phone and travel plans.