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.app vs .io

Which domain extension should you choose? Here's how the two compare — and when each one is the better pick.

.app Google's TLD for apps — and one of the first endings where every site must use HTTPS. .io The ccTLD of the British Indian Ocean Territory, adopted by startups and developers because "I/O" means input/output.

Side by side

.app.io
What it isGeneric TLD, since 2015British Indian Ocean Territory's ccTLD
Runs the registryCharleston Road Registry Inc.Internet Computer Bureau Limited
In the root zone sinceJuly 2, 2015Early ccTLD (date not recorded)
Popular meaning—input/output — the startup and developer favorite
Search geotargetingGeneric — not tied to a countryccTLD that Google treats as generic
DNSSEC-signedYesYes
Name servers (IPv6)5 (5)4 (4)

Choose .app if…

  • Mobile and web apps
  • Product landing pages and download links
  • Developers who want security on by default

Watch out for

  • Sites must be served over HTTPS — plain HTTP won't load in modern browsers
  • Popular one-word names are often premium-priced

A clean, modern ending for apps and software products. The built-in HTTPS requirement is a feature, not a hurdle.

Everything about .app → Register a .app domain ↗.app WHOIS lookup ↗Sell .app domains via API ↗

Choose .io if…

  • 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

Still a solid choice for developer tools and tech brands, but know that it rests on a territory whose status is changing. For a company meant to last decades, also hold the .com.

Everything about .io → Register a .io domain (British Indian Ocean Territory) ↗.io WHOIS lookup ↗Sell .io domains via API ↗

Check one name on both endings

Type a name and see whether it's free as .app, .io and other endings.

Atak Domain is our sister registrar.

.app vs .io FAQ

Is .app better than .io?

Neither is better across the board. A clean, modern ending for apps and software products. The built-in HTTPS requirement is a feature, not a hurdle. Still a solid choice for developer tools and tech brands, but know that it rests on a territory whose status is changing. For a company meant to last decades, also hold the .com.

Does .app or .io rank better on Google?

Google doesn't give either ending a ranking bonus. What differs is geotargeting: .app is generic — not tied to a country, and .io is cctld that google treats as generic. Content and links matter far more than the TLD.

Can I use both .app and .io?

Yes, and many brands do: register both, pick one as the main site, and redirect the other to it so links and email never go astray.