How to create URL shortener using PHP

Basics

URL shortening is a technique in which a lengthy URL  may be made substantially shorter.

Example

http://en.wikipedia.org/w/index.php?title=TinyURL&diff=283621022&oldid=283308287

can be shortened to   http://tinyurl.com/mmw6lb

URL shortening is useful in many cases like twitter you can use 140 characters,so lengthy URLs can be shared when they are shortened.Another use is that shortened url is easier to share rather than long URLs.

There are different methods to shorten the URL,very basic method is to Http redirect to a domain that contains shortened URL.

Here we are going to see how to develop a URL shortener using PHP using http redirect.

Concept

The concept that lies behind this URL shortener is to shrink the lengthy url to small random string of characters,this can be achieved by applying some PHP functions to the lengthy URL.

php-url-shortener

here the lengthy URL string is converted to some four letter words called Key .similarly when the shortened URL is clicked,it should point to the original lengthy URL page.

php url shortener

Base function

First we have to generate random characters(Key) for redirection.The key may base36 ,that contains  26 alphabets and 10 numbers and we can use any hash function to generate key,I have used base_convert function to generate the Key.

string base_convert ( string $number , int $frombase , int $tobase )

The base_convert() function converts a number from one base to another.we convert to base36 format.

Files

index.php – The home page of Shortener,User provides long url

shorten.php – Gets the long URL from index.php and shrinks it

.htaccess – When a shortened URL is clicked ,this file gets the clicked URL and sends to decoder.php

decoder.php – decodes the shortened URL and redirects to correct page

Database structure

This is the database structure which we use to store the data.

ID field is a random 5 digit number

Url field contains the lengthy URL address

shortened field contains the key value corresponding to the unique id

Every time a URL is shortened,the url,key,a random number is inserted into the table.Vice versa if a shortened url is clicked the decode.php will fetch the corresponding url from the table using the unique key

index.php

 Url:

shorten.php

< ?php

$con = mysql_connect("localhost","username","password");
if (!$con)
  {
  die('Could not connect: ' . mysql_error());
  }
mysql_select_db("DB NAME", $con); //Replace with your MySQL DB Name
$urlinput=mysql_real_escape_string($_POST['url']);
$id=rand(10000,99999);
$shorturl=base_convert($id,20,36);
$sql = "insert into TABLE NAME values('$id','$urlinput','$shorturl')";
mysql_query($sql,$con);
echo "Shortened url is http://devlup.com/". $shorturl ."";
mysql_close($con);
?>

.htaccess

Options +FollowSymLinks -Indexes -MultiViews
RewriteEngine on
#
# Internally rewrite shortened URL requests to de-shortened URL lookup script filepath plus query string
RewriteRule ^([\w\d]{4})$ decoder.php?decode=$1 [L]

decoder.php

< ?php

$con = mysql_connect("localhost","username","password");
if (!$con)
  {
  die('Could not connect: ' . mysql_error());
  }
mysql_select_db("DB NAME", $con); //Replace with your MySQL DB Name

$de= mysql_real_escape_string($_GET["decode"]);

$sql = 'select * from TABLE NAME where shortened="$de"';

$result=mysql_query("select * from TABLE NAME where shortened='$de'");

while($row = mysql_fetch_array($result))
{
$res=$row['url'];
header("location:".$res);
}
?>

Demo

http://projects.devlup.com/url/

Download

http://www.box.net/shared/u4ryl4gv6e