The Screaming Frog SEO Spider is a website crawler, that allows you to crawl websites' URLs and fetch key elements to analyse and audit technical and onsite SEO.
Using Screaming Frog to crawl other peoples websites, finding broken links and either using that as an 'in' to get a link from them, or finding out what resource used to be on that page, rewriting it to make it better, and contacting other sites telling them to link to your page on the subject.
