.com vs .io vs .ai vs .co vs .app vs .dev: Which Domain Extension Should You Pick?

.com is still the default in most people’s heads. When someone hears a brand and guesses a URL, they usually try .com first.

Common use: almost any business, especially consumer-facing companies, local services, and anything where strangers must type the name from memory.

Trust / recognition: highest for a general audience. A clean .com rarely needs explanation.

Tradeoff: inventory is scarce. Many short dictionary words are taken or sold as aftermarket names.

If you can get a clean, brandable .com at a normal registration price, it is still the safest everyday choice.

.io started as the country code for the British Indian Ocean Territory and became popular with developer tools, SaaS, and startups that wanted a short available string when .com was gone.

Common use: tech products, APIs, games, and “tooling” brands.

Trust / recognition: strong inside tech circles; weaker with grandparents and some offline businesses. Outside tech, people sometimes ask whether it’s a typo.

Tradeoff: renewals are often higher than a standard .com. Know the renewal before you build the brand around it.

Choose .io when your audience already lives on GitHub and Product Hunt — not when your customers mostly find you via a paper flyer.

.ai is Anguilla’s country code and became the fashionable extension for artificial-intelligence products.

Common use: AI tools, ML companies, and products that want the category in the URL.

Trust / recognition: clear category signal in 2020s tech; can feel trendy or narrow if you later pivot away from AI.

Tradeoff: demand pushed many short .ai names into premium pricing. Also, if your product is not AI-related, the extension can confuse people (“is this an AI company?”).

Use .ai when AI is central to the story. Avoid it as a random substitute for a taken .com if you sell something unrelated.

.co is Colombia’s country code and is often marketed as a shorter stand-in for .com.

Common use: startups and consumer brands that missed .com but want a familiar “company” feel.

Trust / recognition: better than obscure new TLDs for many audiences; still second to .com. People sometimes type .com by habit and land on a competitor.

Tradeoff: the “they’ll add .com by mistake” problem is real. If you pick .co, consider whether the matching .com is a parked page, a competitor, or something you can later buy.

.co works best when the second-level name is distinctive enough that a wrong TLD still doesn’t look like a famous brand.

.app is a Google registry TLD aimed at applications.

Common use: mobile apps, web apps, and product marketing sites that want the word “app” in the extension.

Trust / recognition: clear for software; odd for a bakery or a consulting firm.

Critical technical rule: .app is on the HSTS preload list. Browsers expect HTTPS. You cannot casually serve plain HTTP. Plan certificates and hosting that support HTTPS from day one (most modern hosts do).

.app pricing: often higher than a bargain .com promotion; check first-year vs renewal.

.dev is another Google registry TLD aimed at developers.

Common use: docs, engineering blogs, developer tools, staging/marketing sites for technical products.

Trust / recognition: excellent for developer audiences; less ideal as the only public URL for a non-tech local business.

Same HTTPS rule as .app: .dev is HSTS-preloaded. HTTPS is effectively mandatory.

If your primary customer is a developer, .dev can feel on-brand. If your primary customer is not, prefer .com or another general extension.

Patterns you’ll see across registrars:

“Premium” names (registry or aftermarket) can cost far more than the extension’s normal price. See our premium-domains guide for how that works.

A non-.com is a reasonable primary domain when:

• Your audience already expects that extension (dev tools on .io / .dev, AI product on .ai).
• The matching .com is irrelevant or clearly unrelated (not a scam lookalike).
• You will market the full URL (QR codes, link-in-bio, clickable ads) more than spoken word-of-mouth.
• You’re okay teaching the extension once.

It is a weaker choice when:

• Customers hear the name on a call and must type it later.
• You compete with a confusing .com in the same category.
• Offline trust matters more than tech fashion (clinics, law-adjacent services, schools).

1. List 10 name candidates you like (without the extension).
2. Check .com for each.
3. If .com is taken, check whether the taken site is a real business, a parked page, or a reseller listing.
4. Only then try .io / .ai / .co / .app / .dev based on audience fit.
5. Say the full URL out loud: “brand dot eye oh” vs “brand dot com.” Notice which feels less awkward.
6. Confirm renewal price and HTTPS requirements before you print business cards.

The “best” extension is the one your buyers will type correctly and trust. Fashion fades; failed dictation stays in your support queue.