I'm looking to make something that checks if there's a new post on Wordpress, is there a library or any other way to do this?
Seems exceptionally unlikely that there would be an existing library.
Maybe you could parse the RSS feed to determine if anything has been updated.
If it is your blog, maybe you could setup a twitter account that the blog tweets to each time there is a post. Then you could use one of the twitter libraries to watch that twitter account for updates.