.io domain checker and rules
A .io follows the internet's naming standards, like a .com. Worries about its future come from a Chagos Islands treaty that isn't in force; the facts are below. How our checks work
What can a .io name contain?
Letters, numbers and hyphens, up to 63 characters before the .io. The registry's rules say names follow the internet's naming standards.
| Character | Allowed? | Where |
|---|---|---|
| Letters a to z | Yes | Anywhere; capitals don't count |
| Numbers 0 to 9 | Yes | Anywhere, including first |
| Hyphen (-) | Yes | Not first or last; not two in the 3rd and 4th places |
| Accented letters, other scripts | Not stated | The registry's rules don't mention them |
| Spaces, underscores, symbols | No |
Who can register a .io?
Anyone, anywhere: the registry's rules say an applicant may live in any country. Names go first come, first served.[3, 4]
How do you register a .io?
What should you know before you register a .io?
Renewals cost almost double the first year: $28.12, then $51.80 a year at Porkbun. Compare other endings' renewal prices.
| Fact | What it means |
|---|---|
| Changing terms | The registry may change its terms when you renew or transfer |
| Accurate details | False information can get the name canceled |
| Expiry rules | ICANN's restore rules don't cover country endings like .io. Ask your registrar for its grace period |
Will .io domains stop working?
Not now: .io is active, and no retirement has started. A country ending is retired only after its code leaves the ISO 3166 list, and then it gets five years to phase out by default.
| Question | Answer |
|---|---|
| Is the code "IO" still listed? | Yes, as of IANA's November 2024 note |
| What triggered the worry? | A UK treaty, signed May 2025, handing the Chagos Islands to Mauritius |
| Is that treaty in force? | No; UK ratification stalled in April 2026 |
| If "IO" were removed | A 5-year phase-out, extendable to 10 |
What if the .io you want is taken?
Look for close versions, or use the .io dispute policy if the name copies your trademark. Unlike the usual domain dispute rules, bad faith in either registering or using the name is enough.
| Route | What to know |
|---|---|
| Pick another name | The checker shows close versions and other endings that are available with your handles |
| .io dispute | Prove a trademark match, no rights for the owner, and bad-faith registration or use |
| Where to file | The WIPO Arbitration and Mediation Center |
| What a panel can do | Cancel the name or transfer it to you, nothing more |
Sources [7]
Which platforms should you claim with your .io?
The .com first, then GitHub, X, npm and LinkedIn. Once you have the .io, set up email and HTTPS with Using your .io.
Checks the .io, the .com, GitHub, X, npm and LinkedIn in one search.
Sources (15)
- PrimaryPorkbun: domain name pricing, the public price list our checker reads daily
- PrimaryIANA: Root Zone Database, .io, active
- Primarynic.io: .IO domain registry ("Anyone, anywhere can register")
- Primarynic.io: Rules for domain names (sections 2.3 and 3.1)
- Primarynic.io: Support center (registrar services by Name.com)
- Primarynic.io: Terms and conditions (clauses 2.2, 4.1, 19 and 22)
- Primarynic.io: .IO Domain Name Dispute Resolution Policy, last modified (paragraphs 4(a) and 4(i))
- PrimaryRFC 1035: Domain names, implementation and specification (sections 2.3.1, 2.3.3, 2.3.4)
- PrimaryRFC 1123: Requirements for Internet hosts (section 2.1, names may start with a digit)
- PrimaryRFC 5891: Internationalized domain names in applications (section 4.2.3.1, hyphen rules)
- PrimaryICANN: Expired Registration Recovery Policy (applies to generic endings)
- PrimaryICANN blog, Kim Davies (IANA): The Chagos Archipelago and the .io domain
- PrimaryIANA: Retirement of a country-code top-level domain, revised
- PrimaryGOV.UK: UK secures future of vital Diego Garcia military base
- PrimaryHansard: Diego Garcia Military Base and British Indian Ocean Territory Bill, 13 Apr 2026 (archived copy)