.io

Q: What is .io used for?

Technically the ccTLD for the British Indian Ocean Territory, .io has become the go-to domain for tech startups and developer tools. Its popularity stems from the I/O (input/output) association in computing.

Q: Who can register a .io domain?

None; open to all registrants worldwide.

Q: Who manages the .io top-level domain?

The .io TLD is managed by Internet Computer Bureau Ltd (ICB), which is responsible for the registry operations and maintaining the zone file.

Abstract

Few extensions have drifted further from their assigned territory than .io, the country code of the British Indian Ocean Territory. Administered by Internet Computer Bureau Ltd since 1997, it holds approximately 1.5 million domains, the overwhelming majority registered by software companies. The reason is a coincidence of abbreviation: in computing, I/O denotes input and output. Developer tools, APIs, and software-as-a-service products adopted the extension early, and registration remains open worldwide.