Some other gTLD and ccTLD single-letter domains

are also in use, usually as shortcuts

Domain

Current User

Usage

a.co

Amazon.com

Amazon's official URL shortcut. Generally used by Amazon in SMS messages for informing purchasers of activity on an order

a.org

Astana Inc.

 

c.org

change.org

Shortcut to change.org

e.im

MailTime

URL shortcut for MailTime Email Messenger

e.gg

Facebook

 

f.org

FinTech Labs

 

g.co

Google

Google's official URL shortcut

g.cn

Google

Google's official URL shortcut to help Chinese users locate google

k.tt

Citynews SpA

Used as URL shortcut for https://citynews.it local news, owned by Krzysztof K. Wasielewski

m.me

Facebook

Facebook Messenger's official URL shortcut.

n.pr

NPR

URL shortcut for public radio network NPR

o.co

Overstock.com

URL shortcut for Overstock.com.

q.com

CenturyLink

Shortcut to a CenturyLink setup page asking for a Go Code.

s.co

Snap Inc.

Shortcut to Snapchat's download page

s.de

Sparkassen-Finanzportal

Shortcut to sparkasse.de

t.co

Twitter

Twitter's official URL shortcut

t.me

Telegram

Telegram's official URL shortcut

u.ae

United Arab Emirates

The United Arab Emirates' Government portal

v.me

Visa Inc.

Visa's official URL shortcut

w.org

WordPress

Redirects to wordpress.org, has some assets for wordpress.org (under s.w.org) (see for example wordpress.org/news/2013/12/parker/).

y.org

YMCA of the United States

Shortcut to YMCA