I am a technical person working on a side project that works by scraping data from various career websites and builds a database of companies and the relative popularity of skills over time in those companies.
The idea is that 40% of jobs aren't advertised and that my tool can be used as a prospecting tool for recruiters or jobseekers to find companies that would hire someone with their skillset.
However I'm in 2 minds whether or not building a foundation on scraping other sites is good idea or not. Google, Indeed and SkyScanner have all built successfull businesses, even though they were (probably) violating the terms of sites they scraped at the start.
I would love to hear the communities feedback.