.io

Overview

• .io is the country-code top-level domain (ccTLD) nominally assigned to the British Indian Ocean Territory.
• The extension is commonly used outside its territory, especially by technology companies, startups, open-source projects, APIs and browser games.
• Registry services have been provided under the name Internet Computer Bureau (NIC.IO); DNSSEC is supported.

History

• Delegated by IANA in 1997 to British entrepreneur Paul Kane and operated under the Internet Computer Bureau (ICB).
• The first recorded subdomain registration under .io was levi.io in 1998.
• In April 2017 Paul Kane sold ICB to the domain registry services provider Afilias for US$70.17 million.
• In December 2020 Afilias was acquired by Donuts; Donuts was then acquired by private equity firm Ethos Capital in January 2021.
• A security incident in July 2017 allowed a researcher to take control of four of the seven authoritative name servers for .io, demonstrating DNS risk for the zone.
• International dispute and sovereignty developments: a 2021 UN tribunal ruling concluded the UK has no sovereignty over the Chagos Archipelago (which would affect the BIOT ISO code and potentially the .io ccTLD). Mauritius has asserted claims and in October 2024 the UK announced plans to hand sovereignty to Mauritius once a treaty is finalised; this has raised the prospect that the .io ccTLD might be phased out under IANA/ISO rules (a phase-out would take years).

Usage and Audience

• Common audiences:
  • Tech startups and developer-focused services (the letters "IO" or "I/O" resonate with "input/output").
  • Open-source projects, APIs and developer tools.
  • Browser-based multiplayer games (the rise of "Agar.io", "Slither.io" and other ".io games" popularised the extension).
  • Cryptocurrency-related companies and domain-hack uses.
• Popular examples and phenomena:
  • Itch.io — a prominent platform for indie games using .io.
  • .io games: Agar.io (2015) and Slither.io (2016) spawned many successors (Diep.io, Surviv.io, ZombsRoyale.io, etc.).
• Scale: the TLD has enjoyed commercial success with hundreds of thousands of registrations (sources cite more than ~270,000 domains registered).

Registration Rules

• Eligibility & structure:

  • Second-level registrations are available to individuals and organisations worldwide; no residency in the British Indian Ocean Territory is required for 2nd-level registrations.
  • Third-level registrations (under specific 2LDs) are restricted to residents of the British Indian Ocean Territory; because there are no permanent inhabitants, third-level registrations are effectively unavailable.
  • There are no general residency restrictions for second-level registrations.

• Allowed characters & name length:

  • Labels may contain only alphanumeric characters and hyphens.
  • Labels must be between 3 and 63 characters long.
  • Domain names cannot begin or end with a hyphen and may not contain two consecutive hyphens.
  • The entire domain name may not exceed 253 characters.

• Registration periods, pricing & other restrictions:

  • Minimum registration: 1 year; maximum: 5 years.
  • Pricing is higher than many other TLDs; an indicated price (as of mid‑2023) is about US$36 per year for a new registration.
  • Acceptable use: NIC.IO rules prohibit use "for any purpose that is sexual or pornographic or that is against the statutory laws of any nation," and reserve the right to deactivate offending registrations.

SEO and Brand Impact

• Search engines and ad tools:
  • Google treats .io as a generic top-level domain (gTLD) for targeting purposes because many users and site owners treat it as generic rather than country-specific.
• Brand positioning:
  • The short, two-letter extension and the association with "I/O" make .io attractive to technology brands and developer-focused services.
  • Its relative availability compared with crowded gTLDs and ccTLDs makes it useful for startups seeking short, memorable domains.

Notable Cases or Examples

• High-profile sites and trends:

  • levi.io — one of the earliest recorded subdomain registrations (1998).
  • Itch.io — major indie game platform hosted on .io.
  • Agar.io and Slither.io — games that spawned the ".io games" genre and drove awareness of the TLD.

• Controversy and governance disputes:

  • Revenue and benefit disputes: public discussion and conflicting statements have occurred over whether registry profits benefited the British Indian Ocean Territory or its former inhabitants.
  • Chagos Islanders / legal challenges: the Chagos Refugees Group and others have filed complaints and sought repatriation of the .io ccTLD and back royalties, citing human-rights and OECD-guidelines claims.
  • Sovereignty and future of the ccTLD: international rulings and diplomatic developments (including a 2021 tribunal ruling and a 2024 announcement by the UK regarding transfer of sovereignty to Mauritius) have raised questions about the long-term status of the .io ccTLD and whether it could be phased out under IANA/ISO procedures.

% IANA WHOIS server
% for more information on IANA, visit http://www.iana.org
% This query returned 1 object

domain:       IO

organisation: Internet Computer Bureau Limited
address:      c/o Sure (Diego Garcia) Limited
address:      Diego Garcia
address:      British Indian Ocean Territories, PSC 466 Box 59
address:      FPO-AP 96595-0059
address:      British Indian Ocean Territory (the)

contact:      administrative
name:         Internet Administrator
organisation: Internet Computer Bureau Limited
address:      c/o Sure (Diego Garcia) Limited
address:      Diego Garcia
address:      British Indian Ocean Territories, PSC 466 Box 59
address:      FPO-AP 96595-0059
address:      British Indian Ocean Territory (the)
phone:        +246 9398
fax-no:       +246 9398
e-mail:       administrator@nic.io

contact:      technical
name:         Administrator
organisation: Internet Computer Bureau Ltd
address:      Greytown House, 221-227 High Street
address:      Orpington Kent BR6 0NZ
address:      United Kingdom of Great Britain and Northern Ireland (the)
phone:        +44 (0)1689 827505
fax-no:       +44 (0)1689 831478
e-mail:       admin@icb.co.uk

nserver:      A0.NIC.IO 2a01:8840:9e:0:0:0:0:17 65.22.160.17
nserver:      A2.NIC.IO 2a01:8840:a1:0:0:0:0:17 65.22.163.17
nserver:      B0.NIC.IO 2a01:8840:9f:0:0:0:0:17 65.22.161.17
nserver:      C0.NIC.IO 2a01:8840:a0:0:0:0:0:17 65.22.162.17
ds-rdata:     57355 8 2 95a57c3bab7849dbcddf7c72ada71a88146b141110318ca5be672057e865c3e2

whois:        whois.nic.io

status:       ACTIVE
remarks:      Registration information: http://www.nic.io/

created:      1997-09-16
changed:      2023-01-18
source:       IANA