# Crawler Introduction
Please note that in order to start using Crawler you need to have your billing details added (opens new window).
The Crawler is a push system that works with callbacks. You will push urls to your Crawler using the Crawling API and the Crawler will push back the crawled page to your server.
In order to do that, you need to create a webhook (opens new window) url on your server (example: https://myserver.com/proxycrawl) to receive the data from the ProxyCrawl Crawler.
Keep reading to learn how to push data and receive data to and from the Crawler.