A territory's code with a tech accent
.io is the country-code top-level domain for the British Indian Ocean Territory — the Chagos Archipelago in the middle of the Indian Ocean, home to the Diego Garcia military base and no permanent civilian population. Somewhere along the way, software people noticed that "I/O" is shorthand for input/output, and .io became the default home for developer tools, APIs, games and startups that couldn't get the .com they wanted.
The registry is run by Internet Computer Bureau, which Afilias acquired in 2017; Afilias is now part of Identity Digital, one of the largest registry operators in the world.
The Chagos question
In October 2024 the United Kingdom announced it would transfer sovereignty over the Chagos Archipelago to Mauritius, and a treaty followed in 2025. That raised an obvious question for anyone with a .io address: what happens to the domain?
The short answer is that nothing happens automatically. ccTLDs are tied to codes in the ISO 3166-1 list. If the "IO" code were removed some day, ICANN's policy for retiring ccTLDs gives operators years — not weeks — to wind things down. There's no announced plan to retire .io, but it's a real, if slow-moving, risk to weigh for a brand you plan to keep for decades.
Practical advice
Use .io if your audience is technical and the name is great. Keep the matching .com if you can get it, and make sure your email doesn't depend on a single TLD you can't move away from easily.
Good for
- Developer tools, APIs and SaaS products
- Short, available names that are long gone on .com
- Tech audiences who read ".io" as a signal, not a red flag
Watch out for
- Renewal prices are noticeably higher than .com at most registrars
- The territory's sovereignty is moving to Mauritius, which raises long-term questions about the ccTLD
- Non-technical customers may still type .com by habit
.io by the numbers
.io is the country-code top-level domain (ccTLD) for British Indian Ocean Territory, a territory in Eastern Africa.
Outside British Indian Ocean Territory, plenty of people know .io for a different reason: it reads as input/output — the startup and developer favorite. That second meaning doesn't change who's in charge, though. The domain still belongs to British Indian Ocean Territory, and its registry sets the rules.
A little context on British Indian Ocean Territory: the capital is Diego Garcia, the main language is English, the currency is the United States dollar (USD) and the international dialing code is +246.
IANA lists Internet Computer Bureau Limited as the manager of .io, with an address in British Indian Ocean Territory. The registry's website is http://www.nic.io. ccTLD managers set their own policies — who can register, which second-level names exist, pricing to registrars — so those rules differ from country to country.
Under the hood, the root zone points to 4 name servers for .io, every one of them reachable over IPv6. The delegation is DNSSEC-signed, so resolvers can verify that answers for .io haven't been tampered with on the way. Registration data is published over WHOIS (the WHOIS server is whois.nic.io).
Same registry, other endings
1 other TLD shares this operator.
.io vs other endings
.io FAQ
What does .io stand for?
Officially, nothing — it's the ISO 3166-1 code "IO" for the British Indian Ocean Territory. Tech companies adopted it because I/O is common shorthand for input/output.
Is .io going away?
Not today. In 2024 the UK agreed to hand sovereignty of the Chagos Archipelago to Mauritius. ccTLDs follow ISO 3166-1 codes, so if "IO" were ever withdrawn, ICANN's ccTLD retirement policy would start a multi-year transition rather than an overnight shutdown. Nothing has been announced.
Why are .io domains so expensive?
The registry sets a higher wholesale price than most generic TLDs, and registrars add their margin on top. Strong demand from tech companies has let that price hold — and short or dictionary-word .io names are often sold as premiums.
Does Google treat .io as a country domain?
No. Google lists .io among the country-code domains it treats as generic, so a .io site isn't geotargeted to the British Indian Ocean Territory.
What country is .io?
.io is the country-code top-level domain for British Indian Ocean Territory, in Eastern Africa. Online it's also used for input/output — the startup and developer favorite.
What does .io mean in an email address?
Only that the sender's domain is registered under .io. Because .io is also used for input/output, it doesn't necessarily mean the person is in British Indian Ocean Territory.
Who owns the .io domain?
IANA lists Internet Computer Bureau Limited as the manager of .io: it runs the registry and sets the rules for British Indian Ocean Territory's ccTLD. Individual .io names belong to whoever registers them.
Can I register a .io domain from the US?
It depends on Internet Computer Bureau Limited's policy. Some ccTLDs are open to anyone in the world, while others require a local address, company or trademark. Check the registry (http://www.nic.io) or an accredited registrar before you buy.
Is .io DNSSEC-signed?
Yes. The root zone has a DS record for .io, so DNSSEC validation works all the way down from the root.
How do I look up who owns a .io domain?
Query the registry's registration data service: the WHOIS server is whois.nic.io. Many registrants use privacy services, so personal details may be hidden.
Sources
Data from IANA root zone version 2026102000. Last changed October 21, 2026. Spotted something wrong? Tell us.
