Best eSIM for Southeast Asia: Thailand, Vietnam, Indonesia, Singapore

If you're island-hopping or hitting multiple SEA capitals on one trip, buy a regional eSIM rather than four single-country ones. Three options actually worth using:

• Airalo Connect Asia — 10 GB / 30 days, $18. Covers 14 Asian countries.
• Holafly Asia — 7 days unlimited, $47. Steep but no thinking required.
• Redteago SEA — cheapest, partner quality varies wildly.

Per-country notes

• Thailand — local carriers (AIS, dtac) sell their own tourist SIMs at Suvarnabhumi for ~$10/week. Travel-eSIM prices are competitive; pick whichever has a counter that isn't queued out the door.
• Vietnam — Viettel and Mobifone both work fine on travel eSIMs. Get an eSIM before flying; counters at HAN/SGN are slow.
• Indonesia — outside Jakarta and Bali, 5G is patchy. Telkomsel is the safest bet; Airalo and Holafly both ride it.
• Singapore — Singtel has the best speed; eSIM at Changi is fast at the kiosk if you forget to buy ahead.
• Philippines — Globe and Smart split the country; outer islands favour Smart. Airalo routes via Globe.

Tips

• Customs cards require a phone number. Save your home number to type in, even when roaming-off — the form doesn't validate.
• Grab and Gojek are the lifeline. Both accept e-wallets you can fund with a credit card or PayPal. The eSIM data plan keeps them fed.
• Internet outages during the rainy season are routine. Buy a buffer GB.

For repeat trips, a programmable card pays off fast — load Airalo Connect for two weeks, then switch to Holafly for the wedding trip without buying a new card.