According to the recent LinkedIn court case, it's legal (at least in US) https://arstechnica.com/tech-policy/2017/08/court-rejects-linkedin-claim-that-unauthor

According to the recent LinkedIn court case, it's legal (at least in US) https://arstechnica.com/tech-policy/2017/08/court-rejects-linkedin-claim-that-unauthorized-scraping-is-hacking/ https://arstechnica.com/tech-policy/2017/08/court-rejects-li...