.co vs .io

.co is twice the size of .io: 3,370,530 domains in August 2025 against about 1.37 million in October 2026. .co grew 3.5% in a year; .io grew 20% since September 2025, by independent estimates.

.co is the country code of Colombia, run by MinTIC. .io is the country code of the British Indian Ocean Territory, run by Internet Computer Bureau.