NIC.IO -- .IO Domain Registry
Introduced16 September 1997
TLD typeCountry code top-level domain
RegistryInternet Computer Bureau Ltd
Intended useEntities connected with the British Indian Ocean Territory
Actual usePopular with startup companies, browser games
Registration restrictionsNone for 2nd level registrations; 3rd level registrant must be resident of British Indian Ocean Territory
StructureRegistrations are taken directly at the second level or at third level beneath various 2nd-level labels
DocumentsTerms & Conditions; Rules
Dispute policiesDispute Resolution Policy
Registry websiteNIC.io

The Internet country code top-level domain (ccTLD) .io is nominally assigned to the British Indian Ocean Territory.[1] The domain is managed by Internet Computer Bureau Ltd, a domain name registry, with registrar services provided by Name.com.[2]

Google's ad targeting treats .io as a generic top-level domain (gTLD) because "users and website owners frequently see [the domain] as being more generic than country-targeted."[3]


The .io domain was delegated by the Internet Assigned Numbers Authority to British entrepreneur Paul Kane in 1997 together with the ccTLDs .ac (Ascension Island), .sh (St Helena), and .tm (Turkmenistan). Kane operated them for private benefit under the trade name "Internet Computer Bureau" from 1997 until 2017.[4] In 2014, Kane claimed that "profits are distributed to the authorities for them to operate services as they see fit" and that "Each of the overseas territories has an account and the funds are deposited there because obviously the territories have expenses that they incur and it’s offsetting that." However the UK government has repeatedly stated that this is untrue: “There is no agreement between the UK Government and ICB regarding the administration of the .io domain” and "the Government receives no revenues from the sales or administration of this domain."[5][6] The first subdomain was registered under .IO in 1998, when Levi Strauss & Co. registered the domain levi.io.[7]

In April 2017, Paul Kane sold the Internet Computer Bureau holding company to privately held domain name registry services provider Afilias for $70.17m in cash.[8]

In December 2020, Afilias' owner Hal Lubsen sold it to privately held Donuts for an undisclosed sum.[9]

One month later, in January 2021, Donuts was acquired by private equity firm Ethos Capital, again for an undisclosed sum.[9]

In 2021, the United Nations' International Tribunal for the Law of the Sea ruled that the United Kingdom has no sovereignty over the Chagos Archipelago, and that sovereignty instead belongs to Mauritius. This would extinguish the British Indian Ocean Territory, and the IO ISO-3166 two-letter country code and .io domain could also be extinguished. The United Kingdom, which was not a party to the case, disputes and does not recognise the tribunal's decision, so further legal processes are likely.[10][11] In 2022, the Mauritian government was considering how to progress the issue.[12]

In July 2021, the Chagos Refugees Group UK submitted a complaint to the Irish government against domain-name speculators Paul Kane and Ethos Capital subsidiary Afilias, seeking repatriation of the .IO ("Indian Ocean") country-code top-level domain and payment of back royalties from the $7m/year in revenue generated by the domain.[13] While attempts to repatriate top-level domains are not uncommon, this one is notable in that it cites consumer and human rights violations of the OECD's 2011 Guidelines for Multinational Enterprises rather than multistakeholder representation under ICANN policy, and because the .io domain has enjoyed commercial success, particularly among cryptocurrency companies, with more than 270,000 domains registered.[8][14][15]

Registration and restrictions

Individuals and organisations are allowed to register .io domains.

Labels for .io domains may only contain alphanumeric characters and hyphens, and must be between 3 and 63 characters long. Domain names cannot begin or end with a hyphen symbol, and may not contain two consecutive hyphens. The entire domain name may not contain more than 253 characters.[16]

Applicants for the registration of .io domains do not need to be registered or established in the British Indian Ocean Territory. Third-level domains, such as "xyz.com.io", can only be registered by an inhabitant of the area. (Since there are no legal, permanent inhabitants of the British Indian Ocean Territory, theoretically no third-level domains will be registered.) Any second-level domains used by NIC.IO and top-level domains cannot be used as a third-level domain. For example, the domains "com.com.io", "org.com.io", and "biz.com.io" are all restricted.[17]

Domain names in .io may not be used, "for any purpose that is sexual or pornographic or that is against the statutory laws of any nation." If this requirement is breached, "NIC.IO reserves the right to immediately deactivate the offending registration."[18]

.io domains may be registered for a minimum of one year, and a maximum of 5 years.[19]

Domain names in .io are priced higher than those in many other TLDs. Registering an available .io-domain currently (as of 16 June 2023) costs US$36 per year.[18]


The .io domain is used almost exclusively for purposes unrelated to the British Indian Ocean Territory.

In computer science, "IO" or "I/O" is commonly used as an abbreviation for input/output, which makes the .io domain desirable for services that want to be associated with technology. .io domains are often used for open source projects, application programming interfaces ("APIs"), startup companies, browser games, and other online services.[20]

The TLD is also used for domain hacks, as the letters "io" are an ending of many English terms. For example, Rub.io is a shortened URL that was used for the 2016 U.S. presidential campaign of Marco Rubio.

One reason given for the TLD's popularity is that it stands out by being shorter than other TLDs. Also, the .io TLD is less occupied than other TLDs, so it is more likely that a given term is available there.[21]

.io games

Around 2015 a multiplayer game, Agar.io, spawned many other games with a similar multiplayer playstyle that used the .io domain, such as Diep.io, Slither.io, Surviv.io, and ZombsRoyale.io. Such games are collectively called ".io games".[22]


According to a 2014 Gigaom interview with Paul Kane, then chairman of the Internet Computer Bureau, the domain name registry is required to give some of its profits to the British government, for administration of the British Indian Ocean Territory.[23] After being questioned as a result of the interview, the British Government denied receiving any funds from the sale of .io domain names, and argued that consequently, the profits could not be shared with the Chagossians, the former inhabitants forcibly removed by the British government.[24] Kane, however, contradicted the government's denial.[25][26]


  1. ^ IDN Code Points Policy for the .IO Top Level Domain (PDF), NIC.IO, archived from the original (PDF) on 18 December 2005, retrieved 11 December 2005
  2. ^ "NIC.IO - The Official .IO Domain Registry and Network Information Centre". nic.io. Retrieved 5 December 2023.
  3. ^ "Managing multi-regional and multilingual sites". Archived from the original on 5 October 2019. Retrieved 5 October 2019.
  4. ^ Bridle, James. ".IO: British Indian Ocean Territory". Citizen Ex. Archived from the original on 2 July 2021. Retrieved 2 August 2021.
  5. ^ "British Indian Ocean Territory". UK House of Lords. 10 July 2014. Question (Asked by Lord Avebury): What plans have Her Majesty's Government to share the revenues from the sale of the domain name .io with the people of the Chagos Archipelago including the descendants of those who were evicted from the islands? Answer: The Senior Minister of State, Department for Communities and Local Government & Foreign and Commonwealth Office (Baroness Warsi): 'In much the same way as the .uk domain, the administration of the .io domain has always been carried out by a private sector organisation – this is currently the Internet Computer Bureau. As with the .uk domain, the Government receives no revenues from the sales or administration of this domain, and there are therefore no plans to share these with Chagossians.'
  6. ^ Bridle, James (8 April 2015). "FREEDOM OF INFORMATION ACT 2000 REQUEST REF: 0347-15". Retrieved 17 July 2015. There is no agreement between the UK Government and ICB regarding the administration of the .io domain. ICB independently registered the .io domain through the internet governing process – the Internet Assigned Numbers Authority (IANA) – in the late 1990s. Neither the UK Government nor the BIOT Administration receives revenue from the sale of .io domains, which are administered independently by ICB.
  7. ^ https://www.whois-search.com/whois/levi.io
  8. ^ a b Murphy, Kevin (9 November 2018). "Afilias bought .io for $70 million". Domain Incite. Retrieved 13 August 2020.
  9. ^ a b Allemann, Andrew (22 January 2021). "Breaking: Ethos Capital acquires Donuts". DomainNameWire. Retrieved 2 August 2021. Donuts acquired Afilias last month, and it made sense that Ethos was involved in the deal on the back end. Ethos had investors eager to put money to work in the domain name business after the .org deal fell through. Akram Attallah, CEO of Donuts, told me today that the company's main focus going forward is working on the integration of Afilias.
  10. ^ Harding, Andrew (28 January 2021). "UN court rules UK has no sovereignty over Chagos islands". BBC News. Retrieved 1 February 2021.
  11. ^ Mortensen, James; Bashfield, Samuel (21 January 2021). "The Diego Garcia dispute hits cyberspace". The Interpreter. Lowy Institute. Retrieved 1 February 2021.
  12. ^ Bowcott, Owen (21 March 2022). "Mauritius challenges UK rights over Indian Ocean domain name". The Guardian. Retrieved 21 March 2022.
  13. ^ Levy, Jonathan. "COMPLAINT FILED AGAINST Afilias Ltd. (Ireland) including its subsidiaries 101domain GRS Limited (Ireland), Internet Computer Bureau Limited (England & British Indian Ocean Territory) In Respect of OECD Guidelines Violations in Operation of ccTLD .io BEFORE THE IRELAND OECD NATIONAL CONTACT POINT" (PDF). Chagos Refugees Group UK. Retrieved 2 August 2021.
  14. ^ Goldstein, David (30 July 2021). "Chagos Islanders Lodge Complaint With OECD to Get Their .IO Back". Goldstein Report. Retrieved 2 August 2021.
  15. ^ McCarthy, Kieren (27 May 2019). "Uh-oh .io: Question mark hangs over trendy tech startup domains as UN condemns British empire hangover". The Register.
  16. ^ RFC 1035, Domain names--Implementation and specification, P. Mockapetris (Nov 1987)
  17. ^ "RULES for the .IO Domain and Sub-Domains". Archived from the original on 23 October 2005. Retrieved 30 July 2005.
  18. ^ a b "Cheapest .io Domain Registration, Renewal, Transfer Prices | TLD-List". spaceship.com. Archived from the original on 29 May 2023. Retrieved 29 May 2023.
  19. ^ ".IO Domain Name Registration price list". nic.io. Archived from the original on 22 January 2017. Retrieved 2 October 2016.
  20. ^ "IO Domains in Alexa Top 1 Million". Archived from the original on 27 May 2015. Retrieved 27 May 2015.
  21. ^ "Why are startups turning to .IO?". Name.com Blog. 17 October 2013. Archived from the original on 4 April 2017. Retrieved 5 April 2017.
  22. ^ Takahashi, Dean (2017). "The surprising momentum behind games like Agar.io". VentureBeat. Retrieved 5 May 2018.
  23. ^ David Meyer (30 June 2014). "The dark side of .io: How the U.K. is making web domain profits from a shady Cold War land deal". gigaom.com. Archived from the original on 5 September 2014. Retrieved 6 September 2014.
  24. ^ ICT.IO (26 October 2016). "The dark side of the .io extension". ict.io. Retrieved 19 October 2022.
  25. ^ "House of Lords Summer Recess 2014 Written Answers and Statements". parliament.uk. 11 August 2014. Archived from the original on 4 April 2019. Retrieved 4 April 2019.
  26. ^ David Meyer (11 July 2014). "UK government denies receiving .io domain profits". gigaom.com. Archived from the original on 1 May 2015. Retrieved 19 May 2015.