Is there a developers api for craigslist.org [closed]

Ultimately no. You can query for listings with a search string from an RSS feed such as this:

http://YOURCITY.craigslist.org/search/sss?format=rss&query=SearchString

As far as posting, craiglist has not opened their API. However, this SO Question may shed some light and a possible solution - although not a very reliable one.

Craigslist Automated Posting API?

Write a note to craigslist asking them to open their API,

Craigslist does have a "bulk posting interface" which allows for multiple posts to happen at once through HTTPS POST. See:

http://www.craigslist.org/about/bulk_posting_interface

Craiglist is pretty stingy with their data , they even go out of their way to block scraping. If you use ruby here is a gem I wrote to help scrape craiglist data you can search through multiple cities , calculate average price ect...