# AvailableWhois > AvailableWhois (https://availablewhois.com) is a free domain name availability checker. Type a name and it checks 16 popular TLDs at once (118 in the catalog, plus domain hacks), using live registry RDAP data with a DNS fallback, and says where each answer came from. No signup; searches aren't sold or used to front-run registrations. Each result has a `status` and a `source`: - `available`: The registry has no record of the domain (or, for TLDs without RDAP, DNS shows no delegation). It can be registered. - `taken`: The domain is registered. - `unknown`: Could not be determined (registry slow, rate-limited or unreadable, and DNS was ambiguous); the app shows this as Unsure. Retry later. See `note`. - `invalid`: Not a syntactically valid domain, or the TLD doesn't exist. See `note`. - source `registry`: Authoritative answer from the TLD registry's RDAP service. - source `dns`: Inferred from DNS (nameservers present → taken; NXDOMAIN → likely available). Less certain than `registry`. Agents can call the API directly (no key, max 12 domains per request, rate-limited per IP): ```sh curl -s 'https://availablewhois.com/api/check?d=acme.com,acme.ai,acme.dev&format=json' ``` To send a person to the tool with a name pre-filled, link to https://availablewhois.com/?q=. ## Docs - [AvailableWhois home](https://availablewhois.com/index.md): what the tool does, how verdicts work, and the full API reference. - [How Domain Availability Checks Work](https://availablewhois.com/how-it-works.md): How AvailableWhois checks domain availability: live registry (RDAP) lookups, a DNS cross-check, and a verdict that names its source. No signup, no front-running. - [Domain Availability FAQ](https://availablewhois.com/faq.md): Answers about checking domain availability: how accurate it is, what RDAP is, when expired domains drop, domain hacks, and which TLD to pick. - [Domain Hacks: Examples & How to Find One](https://availablewhois.com/domain-hacks.md): Domain hacks use the TLD to finish the word, like youtu.be or del.icio.us. See famous examples, how to find one for your name, and what to check first. - [How to Choose a Startup Domain Name](https://availablewhois.com/tips.md): Eight practical tips for choosing a startup domain name: keep it short, check every TLD, mind trademarks and renewals, and buy before you announce. ## TLD guides - [TLD Guide: Which Domain Extension to Choose](https://availablewhois.com/tlds.md): Compare popular domain extensions: .com, .ai, .io, .co, .dev, .app, .sh and more. Who each TLD suits and what to know before you buy. - [.com](https://availablewhois.com/tlds/com.md): Generic. Best for Anyone, anywhere. The default people type. Short names are rare, so expect to add a word or pay a premium. - [.ai](https://availablewhois.com/tlds/ai.md): Anguilla ccTLD. Best for AI products. Open to everyone worldwide. Historically sold in 2-year minimum terms and usually priced above .com. - [.io](https://availablewhois.com/tlds/io.md): British Indian Ocean Territory ccTLD. Best for Developer tools, SaaS. A tech favorite for a decade. The 2024 Chagos sovereignty agreement raised questions about its long-term future; worth watching. - [.co](https://availablewhois.com/tlds/co.md): Colombia ccTLD. Best for Startups, companies. Marketed globally as "company". Easy to mistype as .com, so watch for leaked email. - [.dev](https://availablewhois.com/tlds/dev.md): Generic (Google Registry). Best for Developers, docs, side projects. HSTS-preloaded: browsers only load it over HTTPS, so you need a TLS certificate from day one. - [.app](https://availablewhois.com/tlds/app.md): Generic (Google Registry). Best for Web and mobile apps. Also HSTS-preloaded, so HTTPS is mandatory. - [.so](https://availablewhois.com/tlds/so.md): Somalia ccTLD. Best for Productivity and tools. Short and readable. Notion famously ran on notion.so for years. - [.sh](https://availablewhois.com/tlds/sh.md): Saint Helena ccTLD. Best for CLIs, infra, dev tools. A nod to shell scripts. Handy for domain hacks that end in -sh. - [.xyz](https://availablewhois.com/tlds/xyz.md): Generic. Best for Experiments, web3, catch-alls. Huge inventory, so short names are still around. Alphabet uses abc.xyz. - [.me](https://availablewhois.com/tlds/me.md): Montenegro ccTLD. Best for Personal sites, portfolios. Reads naturally in phrases like about.me or hire.me. - [.gg](https://availablewhois.com/tlds/gg.md): Guernsey ccTLD. Best for Gaming, communities. "Good game". Popular with esports and Discord-adjacent projects. - [.tv](https://availablewhois.com/tlds/tv.md): Tuvalu ccTLD. Best for Video, streaming, creators. Twitch made it famous. Revenue is a meaningful income source for Tuvalu. - [.fm](https://availablewhois.com/tlds/fm.md): Micronesia ccTLD. Best for Podcasts, radio, audio. Reads as "FM radio". A natural fit for podcasts and audio apps. - [.tech](https://availablewhois.com/tlds/tech.md): Generic. Best for Tech companies, hardware, events. Says what you do. Generic TLD with plenty of short names left. - [.net](https://availablewhois.com/tlds/net.md): Generic. Best for Networks, infra, fallback for .com. Original 1985 TLD, run by Verisign. Fine as a fallback, rarely a first choice. - [.org](https://availablewhois.com/tlds/org.md): Generic. Best for Open source, nonprofits, communities. Open to anyone; no nonprofit status required. ## API - [OpenAPI 3.1 spec](https://availablewhois.com/openapi.json): GET /api/check (NDJSON stream or `format=json`) and GET /api/health. - [API reference](https://availablewhois.com/index.md): parameters, curl examples, DomainResult fields, errors and limits. ## Optional - [llms-full.txt](https://availablewhois.com/llms-full.txt): every page above in one Markdown file. - [Sitemap](https://availablewhois.com/sitemap.xml): canonical HTML pages.