Im looking for an API to build a site with many pages – to build traffic to by hardworkerneeded

Im looking for some good API’s – I want to build some sites with thousands of pages. I want to make the URLS seo friendly. I want to see where is the best place to look at apis and what is out there?… (Budget: $250-$750 USD, Jobs: Graphic Design, HTML, MySQL, PHP, Website Design)