---
title: Best domain extension for a developer project: .dev, .app, .io, .com or .xyz?
description: Which domain ending to pick for a dev tool, app, API or side project: what each costs over three years, which endings only work over HTTPS, where .io stands, whether the ending affects SEO, and how to check every ending for one name at once.
updated: 2026-11-03
---

# Which domain ending for a developer project?

Take the .com if the name is free at a normal price. If it isn't, pick by what you're building: .dev for a developer tool, docs or an API; .app for a product people install or sign in to; .io if you want the familiar dev-tool look and accept that it's a country code with an open question. Google ranks all of them the same way. Two things catch people out: .dev and .app only load over HTTPS, and a cheap first year can hide an expensive renewal, so compare what each costs over three years.

## What each ending costs on Nymwell

Prices on 2026-11-03. "3 years" is the first year plus two renewals.

| Ending | First year → each renewal | 3 years |
| --- | --- | --- |
| .com | US$18.54 → US$28.92 | US$76.38 |
| .dev | US$19.84 → US$30.21 | US$80.26 |
| .app | US$19.84 → US$35.40 | US$90.64 |
| .io | US$70.42 → US$104.14 | US$278.70 |
| .xyz | US$2.98 → US$27.62 | US$58.22 |
| .org | US$13.35 → US$26.32 | US$65.99 |

.ai is sold in 2-year terms at US$259.77 per term, so it isn't in this table; [.ai or .com for an AI startup](https://nymwell.com/en/guides/ai-vs-com-domain/) compares it with .com.

## What to know about each ending

- **.com** is what people type when they guess an address. Check it first, even if you plan to use another ending.
- **.dev** is run by Google Registry, open to anyone, and HTTPS-only (see below). It tells visitors the site is for developers: tools, docs, APIs, a personal portfolio.
- **.app** is also run by Google Registry, open to anyone, and HTTPS-only. It suits a product people install or sign in to.
- **.io** is the country code of the British Indian Ocean Territory. Google treats it as a generic ending, and many developer tools use it. It costs more than the others above, and its long-term future depends on what happens to the territory's country code (see below).
- **.xyz** starts at US$2.98, but each renewal is US$27.62, 9.3 times the first year. Fine for a side project you may drop; budget the renewal if you keep it.
- **.org** is a common choice for open-source projects and non-profits.

## How to choose, step by step

1. **Check one name across endings at once.** On [Nymwell's search](https://nymwell.com/en/search/), type the name without an ending: you get .com, .ai, .dev, .app, .io and .net together, with prices. From a terminal: `npx nymwell check myproject.com myproject.dev myproject.app myproject.io`.
2. **If the .com is available at a normal price, take it.** You can still use another ending as the main address and redirect.
3. **If the .com is taken, pick by what the project is:** .dev for tools, docs and APIs; .app for a product; .io if the name only works there; .ai if AI is the product.
4. **Compare the 3-year column, not the first year.** A first-year discount ends at the first renewal.
5. **Register the ending you'll build on, plus the .com if it's affordable,** and redirect one to the other so nobody else takes the obvious address.

## .dev and .app only work over HTTPS

Google Registry put both endings on the HSTS preload list that browsers ship with. Browsers turn every http:// request for these names into https://, and if the site has no valid certificate the page doesn't load. There's no warning to click through.

- **On a hosting platform:** Vercel, Netlify, Cloudflare Pages and GitHub Pages issue the certificate for you once DNS points at them. Until it's issued, the browser shows a connection error. Wait for the host's domain page to show the certificate as issued, then open https://yourname.dev. [Connect your domain to Vercel, Netlify or Cloudflare](https://nymwell.com/en/guides/connect-domain-to-vercel-netlify-cloudflare/) covers the DNS records.
- **On your own server:** install a certificate (for example from Let's Encrypt) before you point DNS at the server.
- **You don't configure HSTS yourself.** The ending is already preloaded; you only need a valid certificate.
- **Email isn't affected.** HSTS is a browser rule; MX, SPF and DKIM records work as on any domain. See [email on your own domain](https://nymwell.com/en/guides/custom-domain-email/).

**Local development:** don't invent names like myapp.dev in your hosts file. Browsers force HTTPS for every .dev name, so they fail without a certificate. Use .test or .localhost instead: RFC 6761 reserves both, so they're never registered on the internet, and .localhost names point at your own machine.

## Is .io still safe to register?

- On 22 May 2025, the UK and Mauritius signed an agreement concerning the Chagos Archipelago, the territory .io belongs to, which Mauritius claims as its own.
- Country-code endings follow the ISO 3166-1 list of country codes. If the IO code is removed from that list, IANA's policy is to retire the ending after five years by default, and after ten at most.
- When we checked on 2026-11-03, IANA listed .io as active with no retirement notice.

So a .io works normally today, and any retirement would come years after a code change, with notice. For a project you might rename, that's fine. For a name you'll build a company on, also hold the .com or another generic ending, and keep email on the address you'd keep.

## Does the ending affect SEO?

No. Google says it treats new endings such as .dev, .app and .xyz like .com and .org, and that keywords in the ending give no advantage or disadvantage. It also treats .io, .ai, .co and .me as generic rather than tying them to a country. Pick the ending for the people who'll type and remember it.

## After you buy

1. **Buy the name:** search, review the quote, pay. From Claude Code, the Nymwell plugin does the same in the terminal: see [buy a domain from Claude Code](https://nymwell.com/en/guides/buy-a-domain-from-claude-code/).
2. **Point it at your host** with the records your host shows, then wait for its certificate (essential on .dev and .app).
3. **Open https:// with your name** and check that the padlock shows and www behaves the way you set it.
4. **Set up email** if you'll send from the domain.
5. **Renewal:** new domains on Nymwell renew automatically from 14 days before expiry; you can turn that off on the domain's page. See [domain renewal prices](https://nymwell.com/en/guides/domain-renewal-price/).

## Questions

**Is .dev only for developers?**
No. Google Registry's .dev page lists no eligibility rules, so anyone can register one. The ending simply signals a developer audience.

**Do I need to set up HSTS on a .dev or .app domain?**
No. The whole ending is on the browsers' preload list. You need a valid certificate on every name you serve, including www and any subdomain.

**Can I use .dev for local development?**
Not reliably. Browsers force HTTPS for every .dev name, so a local myapp.dev fails without a certificate. Use .test or .localhost, which RFC 6761 reserves and never assigns.

**Is .io going away?**
Not now. IANA lists it as active. If the IO country code is withdrawn after the UK–Mauritius agreement, IANA's policy allows five years, and at most ten, before the ending is retired.

**Is .xyz bad for SEO?**
No. Google treats new endings like .com. Its cost is the renewal: US$27.62 a year after a US$2.98 first year.

**Which ending is cheapest to keep?**
Compare the 3-year column above rather than the first-year price; the snapshot is dated, and live prices are on the [pricing page](https://nymwell.com/en/pricing/).

## Sources

- Google Registry on .dev (HTTPS required on all connections): https://www.registry.google/domains/dev/
- Google Registry on .app (on the HSTS preload list): https://www.registry.google/domains/app/
- HSTS preload list: https://hstspreload.org/
- RFC 6761, special-use names including .test and .localhost: https://www.rfc-editor.org/rfc/rfc6761
- Google on new top-level domains in Search (2015): https://developers.google.com/search/blog/2015/07/googles-handling-of-new-top-level
- Google on country-code domains it treats as generic: https://developers.google.com/search/docs/specialty/international/managing-multi-regional-sites
- IANA .io record (checked 2026-11-03): https://www.iana.org/domains/root/db/io.html
- IANA on retiring a country-code domain: https://www.iana.org/help/cctld-retirement
- UK–Mauritius agreement concerning the Chagos Archipelago (2025-05-22): https://www.gov.uk/government/publications/ukmauritius-agreement-concerning-the-chagos-archipelago-including-diego-garcia-cs-mauritius-no12025

## Related

- [.ai or .com for an AI startup?](https://nymwell.com/en/guides/ai-vs-com-domain/)
- [Domain renewal prices](https://nymwell.com/en/guides/domain-renewal-price/)
- [Connect your domain to Vercel, Netlify or Cloudflare](https://nymwell.com/en/guides/connect-domain-to-vercel-netlify-cloudflare/)
- [Email on your own domain](https://nymwell.com/en/guides/custom-domain-email/)
- [Buy a domain from Claude Code](https://nymwell.com/en/guides/buy-a-domain-from-claude-code/)