Choose .dev for a developer portfolio, technical blog, documentation site or open-source project; choose .io for a SaaS product, API, developer tool or startup that needs a broader company-shaped brand. .dev says who the site is for, costs less in most registrar catalogs and requires HTTPS. .io has stronger startup recognition but a higher ownership cost and the policy caveat of being a country-code TLD.
Two technical signals with different jobs
The extensions look equally at home in source code, but they communicate different things. .dev is a generic TLD operated by Google Registry and explicitly positioned for developers and technology. .io is the country code for the British Indian Ocean Territory; the computing abbreviation for input/output turned it into an international startup convention. IANA's current delegation records identify Charleston Road Registry for .dev and the Internet Computer Bureau for .io.
That origin matters less than the promise your address makes. A hiring manager reading name.dev expects a person, code or documentation. A buyer reading product.io expects software. Neither promise is mandatory, but matching it reduces the explanation your brand has to do.
.dev vs .io comparison table
| Factor | .dev | .io |
|---|---|---|
| DNS type | Generic TLD (gTLD) | Country-code TLD (ccTLD) |
| Registry | Google Registry / Charleston Road Registry | Internet Computer Bureau Limited |
| Main signal | Developer, code, documentation | Software company, SaaS, input/output |
| Best fit | Portfolios, docs, open source, engineering blogs | Products, APIs, platforms, venture-backed startups |
| HTTPS | Required by TLD-level HSTS preload | Strongly recommended, not imposed by the TLD |
| Search geography | Generic | Treated as generic by Google Search |
| Price posture | Usually standard-priced | Usually mid-premium |
| Policy dependency | ICANN gTLD contract | Territory and ccTLD eligibility |
| Non-technical recognition | Literal but niche | Familiar in tech, less clear outside it |
When .dev is the better choice
Use .dev when the audience should understand “developer” before it understands the brand. It works especially well for a personal portfolio, a package manual, an engineering team handbook, a code lab or an open-source project's documentation. The word after the dot becomes a compact category label, which lets the name before it stay short.
The security constraint is also useful when planned for. Google Registry describes .dev as a secure domain for developers, and the whole namespace is on browser HSTS preload lists. Browsers attempt HTTPS from the first connection, so there is no working plain-HTTP fallback. That makes a valid certificate a launch prerequisite, not an optional later task. See the broader HTTPS-only TLD list before using .dev for local test names or a host that cannot issue TLS.
When .io is the better choice
Use .io when the address needs to represent a product or company rather than a profession. Years of adoption by SaaS businesses, API platforms and developer tools have made it a recognizable startup ending. It is flexible enough for a team to move from one product to several without the name sounding like an individual portfolio.
Its two trade-offs are recurring cost and policy exposure. .io renewals are commonly much higher than a standard .dev renewal, so calculate the ownership cost rather than comparing launch promotions. It also remains legally a ccTLD. The UK and Mauritius signed a treaty concerning the Chagos Archipelago in 2025, but it has not entered into force as of this update and IANA's .io delegation is unchanged. The risk is long-term and procedural, not a claim that existing sites are about to stop resolving. The .io reference page tracks that status in more detail.
Decision matrix by project
| Project | Default pick | Reason |
|---|---|---|
| Individual developer portfolio | .dev | The audience and role are immediately clear. |
| Library or framework documentation | .dev | Technical purpose is more valuable than company posture. |
| Open-source community | .dev or .org | .dev signals code; .org signals community governance. |
| Paid SaaS application | .io | Reads as a product company rather than documentation. |
| API platform | .io | Input/output association reinforces the product. |
| Developer agency | Depends | .dev for specialist positioning; .io for a scalable studio brand. |
| Local development environment | Neither | Use a reserved testing name; .dev forces public-browser HTTPS behavior. |
SEO and five-year cost
There is no generic-TLD ranking bonus hidden in .dev, and “io” is not an algorithmic software keyword. Google currently includes .io in its published list of ccTLDs treated as generic, so both can serve a global audience. Content, links, technical accessibility and brand response do the ranking work.
For cost, record three numbers: today's registration charge, the ordinary renewal charge and any premium renewal attached to the exact label. Multiply the renewal—not the sale price—across the expected ownership period. Our renewal-cost guide provides the formula. If a .io name costs several times the matching .dev but does not improve the product story, spend the difference on the site.