What Is .io?
The .io domain is the country code top-level domain for the British Indian Ocean Territory. However, its cultural significance comes from computer science — 'I/O' stands for 'input/output,' a fundamental concept in programming. This association has made .io one of the most popular startup and developer domains.
The extension gained massive traction in the 2010s as tech startups sought alternatives to expensive .com names. Companies like GitHub (originally at github.io for pages), Socket.io, and hundreds of SaaS products helped establish .io as the de facto tech startup extension.
The .io aftermarket is robust with NameBio recording 233+ sales. Brandable .io domains typically sell in the $1,000–$5,000 range, while premium short names command significantly more.
Notion started on notion.so before moving to notion.io and eventually notion.com. Many SaaS products launch on .io first.
Why This Matters for Startups
After .com, .io is arguably the most recognized tech startup extension. It signals that you're building a technology product, and it's widely accepted by investors, developers, and tech-savvy customers. If your ideal .com is unavailable or too expensive, .io is the strongest alternative for most tech startups. Prices are reasonable — good brandable .io names can be found in the $1,000–$5,000 range.
Find Your Perfect Domain
Browse premium domains on this and other popular extensions, hand-picked for startups.
Browse Domains