Add spam filtering ASAP. In the past I had created a URL shortner, even created an API and the usage exploded but most of the links were created by spammers and

Add spam filtering ASAP. In the past I had created a URL shortner, even created an API and the usage exploded but most of the links were created by spammers and I used to get regular warnings from my host. In the end I just shut the whole thing down. if you just want to shorten the links with your own short domain, better use bit.ly. They even have basic analytics and it's free.