A crawling developer designs, builds, and maintains web crawlers, which are programs that browse the internet systematically to collect specific data. They ensure that these crawlers operate efficiently and effectively, respecting robots.txt rules and website structures. They handle issues such as handling JavaScript, managing CAPTCHAs, handling cookies, and managing sessions. They also process and analyze the data collected, often working with databases and APIs. Their work is essential for tasks such as web indexing, data mining, and data analysis. They often need to have strong skills in programming languages such as Python, Java or PHP.