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.dev vs .app vs .io: Which TLD Is Best for Developer Tools?

Choosing between .dev, .app, and .io matters more than you'd think. Each extension sends different signals, costs different amounts, and comes with different technical requirements. Here's what you need to know to pick the best TLD for developers and tech products.

The basics

All three extensions are widely recognized in tech circles, but they differ in ownership, pricing, and target audience.

.dev is owned by Google and launched in 2019. It costs around $12-15 per year depending on your registrar. Examples include web.dev and opensource.dev. It signals "developer tool" immediately, but some non-technical users may not recognize it as a valid domain.

.app is also owned by Google, launched in 2018. Pricing runs $15-20 per year. You'll see it used by companies like Cash (cash.app) and as a redirect for Notion. It skews more consumer-facing than .dev, with broader recognition outside the developer community.

.io is the OG tech TLD. Originally the country code for British Indian Ocean Territory, it's been adopted universally by startups and tech companies since the early 2010s. Think github.io, itch.io, and linear.io. Pricing is significantly higher at $30-60 per year.

HTTPS requirement

Both .dev and .app are HSTS preloaded at the browser level. This means all domains on these TLDs must use HTTPS—there's no way to serve them over plain HTTP. Browsers will refuse the connection.

For most developers, this is a feature, not a bug. You should be using HTTPS anyway. But it does mean you can't cut corners during local development or on throwaway test servers. You'll need valid certificates from day one.

.io has no such requirement. You can serve it over HTTP if you want (though you shouldn't).

Price and availability

Price matters if you're buying multiple domains or operating on a tight budget.

.dev and .app are newer, so more names are available. Short, memorable combinations are still out there. Premium names exist, but the general pool is less picked over than .io.

.io has been around longer, so the best names are mostly gone. Popular words, short phrases, and anything remotely brandable was claimed years ago. You'll pay premium prices for anything decent on the aftermarket.

If you're browsing available names across all three extensions, Vacant Domains has filtered options for each TLD.

Recognition and perception

.io is the most established. It's been the default choice for developer tools and tech startups for over a decade. Within tech circles, it's universally understood, though some non-technical users may be unfamiliar.

.dev is unambiguous. If you see a .dev domain, you know it's a developer tool or developer-focused service. That clarity is valuable for positioning, but it also limits your audience. Consumer-facing products may feel out of place on .dev.

.app is the middle ground. It works for both technical and non-technical audiences. It suggests an application or product, which is broader than "developer tool." If you're building something that developers use but non-developers also interact with, .app makes sense.

The sovereignty question

.io is a country code TLD (ccTLD) tied to the British Indian Ocean Territory, which may be returned to Mauritius. If that happens, .io's future could be uncertain.

But ccTLDs have outlived their countries before. .su (Soviet Union) still exists decades after the USSR dissolved. ICANN has strong financial incentive to keep .io alive. The risk is real but probably overstated.

If you're choosing a TLD for a long-term project and geopolitical stability matters, .dev or .app are safer.

Audience signal

The most important question: who is your user?

If you're building a CLI tool, API service, code library, or anything where developers are your primary audience, .dev is the clearest signal. It sets expectations immediately.

If you're building a consumer-facing app that happens to have a technical backend, .app works better. It's approachable for non-developers while still being tech-adjacent. Think mobile apps, SaaS products with broad audiences, productivity tools.

If you're building something for either audience, or you want the prestige of the established tech TLD, .io is the safe choice. It carries weight and credibility in the startup ecosystem.

Real tradeoffs

Here's the decision matrix:

Choose .dev if:

  • Your users are primarily developers
  • You want maximum clarity about what your product is
  • You're okay with a narrower perceived audience
  • You want lower registration costs

Choose .app if:

  • Your product has a consumer-facing component
  • You need broader recognition outside tech circles
  • You're building something interactive or user-facing
  • You want to avoid the "developer tool" pigeonhole

Choose .io if:

  • You want the established, credible tech TLD
  • You're willing to pay more for the name
  • You're targeting startups, investors, or the broader tech ecosystem
  • You want a TLD that works for any tech product

What's actually available

All three extensions still have plenty of decent names. The "all good domains are taken" narrative is overblown. You just need to be creative.

Two-word combinations work well. Verb + noun, adjective + noun, or domain hacks where the TLD completes the word. Shorter isn't always better if it's less memorable.

You can browse available domains across .dev, .app, and .io on Vacant Domains.

The real answer

There's no universal "best" choice. It depends on your product, your audience, and your budget.

For most developer tools, .dev is the right call. It's cheap, clear, and purpose-built for your audience. For consumer apps, .app is the better signal. For established startups or products that span both audiences, .io still carries weight despite the higher cost.

Pick the one that matches your positioning. The TLD is part of your brand, and it sets expectations before anyone clicks the link.