Looking for an app that will crawl a website and index every word on the site (internal files only)

Looking for an app that will crawl a website of my choice and index every word on the site (internal files only). For example, I want to enter a URL for a particular site (say cdp.org) and derive an index of how many times the phrase "sustainable investing" occurs on every file on the cdp.org domain.

Does such a thing exist?