Single-letter second-level domain
Single-letter second-level domains are domains in which the second-level domain of the domain name consists of only one letter, such as. In 1993, the Internet Assigned Numbers Authority explicitly reserved all single-letter and single-digit second-level domains under the top-level domains com, net, and org, and grandfathered those that had already been assigned. In December 2005, ICANN considered auctioning these domain names.
Active single-letter domains
On December 1, 1993, the Internet Assigned Numbers Authority explicitly reserved the remaining single-letter and single-digit domain names. The few domains that were already assigned were grandfathered in and continued to exist.The six single-letter domains in existence at that time under.com,.net and.org were the following:
| Domain name | 1993 owner | Current owner |
| i.net | INet Solutions Ltd | Saw.com |
| q.com | JG | Lumen Technologies |
| q.net | Privately owned | Privately owned |
| x.com | Marcel DePaolis & Dave Weinstein | X Corp. |
| x.org | X Consortium | X.Org Foundation |
| z.com | HomePage.com | GMO Internet, Inc. |
The.org TLD was subsequently reopened for single-letter domain registrations. These and selected other gTLD and ccTLD single-letter domain names currently in use, typically as shortcuts, are listed below.
| Domain name | Current user | Usage | - |
| 0.email | Zero Email | - | |
| a.co | Amazon.com | URL shortcut for Amazon, generally used by Amazon in SMS messages for informing purchasers of activity on an order | - |
| a.org | - | ||
| b.mw | BMW | URL shortcut for BMW | - |
| c.ai | character.ai | - | |
| c.cc | Brian Cartmell | Homepage | - |
| c.im | C.IM is a general, mainly English-speaking Mastodon instance. | - | |
| c.org | Change.org | URL shortcut for change.org | - |
| d.gs | Dragonsayen | URL shortcut for dragonsayen.com | - |
| d.tube | DTube | Video sharing platform with peer-to-peer capabilities | - |
| e.gg | Meta Platforms | - | |
| e.im | MailTime | URL shortcut for MailTime Email Messenger | - |
| e.srl | E-Group | Official URL Of E-Group. | - |
| IT services have been provided by since 2005, operating from Bangladesh, Germany, USA, Australia, France, Italy, Libya, Norway, UK, and Ireland. | - | ||
| f.org | FinTech Labs | - | |
| g.cn | Google's official URL shortcut to help Chinese users locate Google | - | |
| g.co | Google's official URL shortcut | - | |
| g.gl | - | ||
| g.gg | Global Grid Gallery | - | |
| g.network | G.Network | London based ISP | - |
| g.org | - | ||
| g.vu | g.vu | An URL Shortener | - |
| h.plus | Unstable Reality | Homepage for the H+ research project, owned by Alessandro Perilli | - |
| A private email identity from Rocket Domains, part of the suite — inspired by sci-fi, civil rights, and digital freedom. | - | ||
| k.at | k-digital Media GmbH & Co KG | Austrian News-portal | - |
| k.im | Kim Dotcom | URL shortcut for x.com/kimdotcom | - |
| k.tt | Citynews SpA | URL shortcut for Citinews | - |
| k.vu | FreeDNS | - | |
| l.ink | Top Level Design | - | |
| m.co | Volvo Cars | Volvo Cars' car sharing service, M | - |
| m.me | Meta Platforms | URL shortcut for Messenger | - |
| m.page | mmm.page | URL shortcut for mmm.page website builder | - |
| n.pr | NPR | URL shortcut for public radio network NPR | - |
| n.school | The New School | Website of The New School in Moscow | - |
| o.co | Overstock.com | URL shortcut for Overstock.com | - |
| q.digital | Q.Digital, Inc. | - | |
| r.nf | An instance of the Lemmy social news aggregator software, previously an instance of Libreddit, a private Reddit frontend. | - | |
| s.co | Snap Inc. | URL shortcut to Snapchat's download page | - |
| s.de | Sparkasse | URL shortcut for sparkasse.de | - |
| s.id | PT Aidi Digital Global | URL Shortener | - |
| s.team | Steam | Quick friend invites on Steam | - |
| t.co | X Corp. | Official URL shortcut of Twitter | - |
| t.ly | t.ly | URL Shortener | - |
| t.me | Telegram | URL shortcut for Telegram | - |
| u.ae | United Arab Emirates | The United Arab Emirates' Government portal | - |
| u.to | u.to | URL Shortener | - |
| v.gd | v.gd | URL shortener | |
| v.me | Visa Inc. | URL shortcut for Visa | - |
| v.org | V Foundation | - | |
| w.org | WordPress | Redirects to wordpress.org, has some assets for wordpress.org | - |
| w.wiki | Wikimedia Foundation | The official Wikimedia Foundation URL Shortener | - |
| x.ai | xAI | Homepage URL | - |
| X | - | ||
| x.company | X Development | Homepage for X Development | - |
| x.team | Shortcut to X Careers, a service at X Development | - | |
| y.gy | URL Shortener and QR Code Creator | - | |
| y.org | YMCA of the United States | Shortcut to YMCA | - |
| z.ai | Z.AI | AI chatbot and coding model | - |
| VPN service | - | ||
| s.ee | URL Shortener | - | |
| b.ls | URL Shortener | - | |
| g.ls | URL Shortener | - | |
| j.ls | URL Shortener | - | |
| q.gg | URL Shortener | - | |
| q.ls | URL Shortener | - | |
| u.ls | URL Shortener | - | |
| w.ls | URL Shortener | - | |
| z.ls | URL Shortener | - | |
| u.nu | URL Shortener | - | |
| 0.sb | URL Shortener | - | |
| 0.tl | URL Shortener | - | |
| 2.pe | URL Shortener | - | |
| 2.sb | URL Shortener | - | |
| 3.sb | URL Shortener | - | |
| 4.sb | URL Shortener | - | |
| 5.st | URL Shortener | - | |
| 6.vu | URL Shortener | - | |
| 7.ls | URL Shortener | - | |
| 8.nf | URL Shortener | - | |
| 9.ms | URL Shortener | - | |
| d.tl | URL Shortener | - | |
| e.gd | URL Shortener | - | |
| f.tl | URL Shortener | - | |
| h.fo | URL Shortener | - | |
| i.vg | URL Shortener | - | |
| j.gt | URL Shortener | - | |
| l.gt | URL Shortener | - | |
| l.nf | URL Shortener | - | |
| l.td | URL Shortener | - | |
| m.bo | URL Shortener | - | |
| n.ms | URL Shortener | - | |
| p.sb | URL Shortener | - | |
| q.cg | URL Shortener | - | |
| r.gl | URL Shortener | - | |
| s.sb | URL Shortener | - | |
| s.tt | URL Shortener | - | |
| u.nf | URL Shortener | - | |
| z.nu | URL Shortener | - | |
| a.ac | URL Shortener | - | |
| a.tt | URL Shortener | - | |
| b.ee | URL Shortener | - | |
| b.lu | URL Shortener | - | |
| c.sk | URL Shortener | - | |
| d.ac | URL Shortener | - | |
| f.bi | URL Shortener | - | |
| h.lu | URL Shortener | - | |
| h.sk | URL Shortener | - | |
| k.sk | URL Shortener | - | |
| l.tt | URL Shortener | - | |
| n.ee | URL Shortener | - | |
| n.lu | URL Shortener | - | |
| q.lu | URL Shortener | - | |
| t.ee | URL Shortener | - | |
| t.lu | URL Shortener | - | |
| t.sc | URL Shortener | - | |
| u.sc | URL Shortener | - | |
| u.sk | URL Shortener | - | |
| v.sc | URL Shortener | - | |
| x.sh | URL Shortener | - | |
| z.ee | URL Shortener | - | |
| z.sh | URL Shortener | - |
Many other single-letter second-level domains have been registered under country code top-level domains. The list of country code top-level domains which have been identified to allow single-letter domains are:
- .ac
- .af
- .ag
- .ai
- .am
- .bo
- .by
- .bz
- .cm
- .cn
- .co
- .cr
- .cx
- .cz
- .de
- .dk
- .fm
- .fr
- .gd
- .gg
- .gl
- .gp
- .gs
- .gt
- .gy
- .hn
- .hr
- .ht
- .ie
- .im
- .io
- .is
- .je
- .kg
- .ki
- .kw
- .la
- .lb
- .lc
- .ly
- .md
- .mg
- .mk
- .mp
- .ms
- .mw
- .mx
- .mu
- .nf
- .np
- .nz
- .pe
- .ph
- .pk
- .pl
- .pn
- .pr
- .pw
- .ro
- .sh
- .st
- .tc
- .tl
- .tt
- .to
- .tv
- .ua
- .uk
- .vc
- .vg
- .vn
- .vu
- .ws