Email Extractor and Hunter extension. EDIT: I should have explained they’re basically email extracting applications which somehow manages to retrieve all the emails linked to a company or organisation whose website you choose to go on. It does so, by retrieving it from articles the company was mentioned in or directly from the desired website.
Can be beneficial to start-ups, companies and other organisations. I’ve personally tested “Hunter” one but you have to give them a professional email address due to spam supposedly.