Lempart Flex is a travel eSIM shop run by Lempart LLC, a small US company. Instead of one plan sized for the heaviest user, it offers the whole range in about 200 destinations: typically from 500 MB to 10 GB a day at full speed, then up to 384 kbps, 512 kbps or 1 Mbps, for 1 to 30 days, plus fixed-data plans. In places like Japan, Thailand and Vietnam you can also choose IP of the country your connection exits from. Buy on the website without an account, or in the iPhone app (Android is coming soon). The eSIM arrives in about a minute and is refundable until it's installed. Pay for the speed you need, not for the biggest plan.