.com vs .io vs .ai vs .app for Startups
Four extensions dominate startup naming for different reasons. Two are generic TLDs with ordinary rules, two are country-code domains or code-driven choices with quirks worth understanding before you build a brand on them.
The four at a glance
Identity matters here more than usual because the operator and the legal basis of each extension affect risk.
| .com | .io | .ai | .app | |
|---|---|---|---|---|
| Type | Generic TLD | Country-code TLD (British Indian Ocean Territory) | Country-code TLD (Anguilla) | Generic (new gTLD) |
| Manager listed by IANA | VeriSign Global Registry Services | Internet Computer Bureau Limited | Government of Anguilla | Charleston Road Registry (Google) |
| Open to anyone | Yes | Yes in practice | Yes in practice | Yes |
| Quirks | Price regulated by agreements with US government and ICANN | Future linked to a sovereignty treaty | Historically a two-year minimum term | HTTPS enforced by browsers (HSTS preload) |
| In ICANN CZDS zone files | Yes | Not as a typical gTLD; check | Not as a typical gTLD; check | Yes |
Manager names come from the IANA root zone database. Operational details below come from secondary reporting and are marked where they should be double-checked with your registrar.
.com: the default with the fewest surprises
.com is operated by Verisign and is the most recognisable extension. Its main advantages are familiarity, user trust and the fact that people mistype other extensions into .com. Its main drawback for a startup is availability: short, clean names are largely taken, so you may face a long name, a prefix such as "get", or an aftermarket purchase.
Price is regulated. Wholesale increases are limited by the .com registry agreement with ICANN and the NTIA cooperative agreement, historically to a fixed percentage per year within defined windows, so renewals tend to be predictable. For the full picture see the .com guide and .com vs .net vs .org.
.io: popular with developers, with an unresolved question
.io is the country-code domain for the British Indian Ocean Territory, but it is used almost entirely as a technology brand extension. IANA lists Internet Computer Bureau Limited as manager, and trade reporting says Identity Digital runs the registry.
The reputational draw is "this is a software company", plus the "input/output" reading. Costs have a reputation for being above generic TLDs and renewals can differ from first-year pricing, so read renewal terms.
The treaty uncertainty
The UK and Mauritius signed a treaty over the Chagos Archipelago in 2025, which led commentators to ask what would happen to .io. Country-code domains follow the ISO 3166-1 list. ICANN policy says that if a code is removed from that list, a retirement process begins and the domain would be removed from the root only after a multi-year period, which can be extended. ICANN wrote about this in 2024. As of the reporting we found, the treaty's implementation was stalled and no official decision had been made about .io itself. This is a low-probability, long-timeline risk rather than an imminent one, but it is a risk a company with a large .io installed base should weigh. If you adopt .io, owning the .com version, where you can, is a cheap hedge.
.ai: the AI-company signal, with rules
.ai is Anguilla's country-code domain; the Government of Anguilla is the manager listed by IANA. Reports say Identity Digital took over operations in 2025 under a revenue-sharing agreement. The extension became popular because the letters match "artificial intelligence".
- Registration terms: .ai has historically required a two-year minimum registration and renewal term. Several sources say this still applies; confirm with your registrar.
- Price pattern: Wholesale cost has risen over time and retail is typically higher than for .com, so budget for the upfront multi-year payment.
- Brand fit: It signals a category strongly. If your product pivots away from AI, the name can feel mismatched.
Because .ai is a country-code domain, it is not part of ICANN's new gTLD programme. Read the comparison of gTLDs, ccTLDs and new gTLDs for how the rules differ, and the .ai guide for details.
.app: a secure-by-default developer extension
.app is a generic extension operated by Google's Charleston Road Registry. IANA shows it delegated in July 2015, and Google's registry page says general availability began on 8 May 2018 (timed to Google I/O). Google states that .app was added to the HSTS preload list before it launched, so modern browsers refuse to load .app sites over plain HTTP.
- Practical effect: You need a valid TLS certificate before any page loads. Most hosts include one, and free certificates are widely available.
- Audience: Targeted at app developers and software products, but open to everyone.
- Trade-off: It is less universally recognised than .com, and typing habits send some visitors to .com.
Compare it with its sibling in .dev vs .app.
Cost and renewal patterns
Prices are best compared as patterns. .com has a regulated wholesale price, so renewals at most registrars stay close to the registration price apart from promotions. .io and .ai are country-code domains whose registries set their own pricing, and both are generally priced above typical generic extensions; .ai also bills in multi-year blocks. .app sits in the premium new-gTLD range and, as with most new extensions, introductory offers can differ from renewal. Always read the registrar's renewal line for the specific extension, and budget for the total over three to five years, not the first invoice.
A second pattern is the premium list. Short or dictionary names in .io, .ai and .app are often priced as premium at registration and sometimes at renewal. A name that looks cheap on a search page can show a very different price at checkout, so look for the premium flag before committing.
Choosing by startup stage
- Pre-launch validation. Use whatever is available and cheap. Moving a domain later is easy for a landing page and hard once users link to it.
- Consumer product. Aim for .com, or a clear .com plus a secondary extension for marketing. Verbal handoff ("dot com") is still the strongest.
- Developer tool or API. .io, .dev or .app read as native to the audience. Register the .com if the budget allows, even if you only redirect it.
- AI product. .ai is widely understood in the category, but compare the total cost of the multi-year term and check whether your target customers care. See the startup TLD guide for a broader framework.
Whatever you choose, register obvious variants early and lock the domain with your registrar. Names that expire are quickly caught; read how to protect your domain from expiring.
Frequently asked questions
Is .io going away?
Not as of the reporting we found. The risk comes from a UK-Mauritius treaty and ICANN's policy that a country-code domain is retired if its code leaves the ISO 3166-1 list, a process that takes several years. No official decision on .io had been announced, so treat it as a long-term uncertainty.
Does .ai really require registering for two years?
It has historically had a two-year minimum for registration and renewal, and sources report it still applies. Confirm the current rule and the total upfront cost with your registrar.
What does HSTS preload mean for a .app domain?
Browsers have .app on a built-in HTTPS-only list, so a site must have a valid TLS certificate to load. Plain HTTP and expired certificates will fail rather than warn quietly.
Should a startup buy .com in addition to .io, .ai or .app?
If it is available at a reasonable price, owning .com is a common hedge against typos and brand confusion. Many companies redirect it to the main site.
Are .io and .ai covered by ICANN zone files?
Country-code TLDs are generally not distributed through ICANN CZDS, so zone-file-based tools may not list them. Check coverage before relying on a tool for those extensions.