Bitly

Bitly is a URL shortening service and a link management platform, and the company Bitly, Inc., was established in 2008. It is privately held and based in New York City. Bitly shortens 600 million links per month, for use in social networking, SMS, and email. Bitly makes money by charging for access to aggregate data created as a result of many people using the shortened URLs.
In 2017, Spectrum Equity acquired majority stake in Bitly for $64 million.
As of August 2018, Bitly had shortened over 37.5 billion URLs.
Products.
The Bitly URL shortening service became popular on Twitter after it became the default URL shortening service on the website on May 6, 2009. It was subsequently replaced by Twitter's own t.co service.
The company behind Bitly launched a similar service, but for online videos, to determine what videos are the most popular on the web.
The company offers a paid solution called Bitly Enterprise that provides advanced branding features, audience intel, omnichannel campaign tracking and more. Companies can use their own custom domains to generate shortened links; for example, "The New York Times" uses codice_1, and Pepsi uses codice_2, Google uses codice_3. This allows the company to push brand awareness on services such as Twitter but use the Bitly engine to generate the shortened URLs and track marketing metrics. Bitly Enterprise also has advanced analytics features and uses Bitly data to provide advanced social insight tools for companies and brands.
Technology.
The company uses HTTP 301 redirects for its links. The shortcuts are intended to be permanent and cannot be changed once they are created. URLs that are shortened with the bitly service use the codice_4 domain or any other generic domain that the service offers. 
Starting October 12, 2010, users could automatically generate QR codes that, when scanned with a mobile QR code reader, automatically directed users to shortened links.
This was later removed.
On May 29, 2012, Bitly announced "Bitmarks", a new search feature, with enhanced public profiles and an iPhone app.
Preview short URLs.
To see a short URL's information, that is to reveal or preview any Bitly URL codice_5 just append a plus sign "codice_6", as in codice_7, for example codice_8 should be copy and pasted into the browser address bar as codice_9.
This allows users to see and check the long URL before visiting it.
Alternative domains.
codice_10 is the country code top-level domain (ccTLD) for Libya. In 2011, the bit.ly address was set to redirect to bitly.com.
The .ly TLD is controlled by the Libyan government, which has previously removed one domain deemed incompatible with Muslim law.
Any shortened URL generated with Bitly can also be accessed by replacing that domain with any one of the following: