Have you ever need to collect data from a website and then you call a freelancer programer? his/her work might be awesome, and you happy with it. but a for example after 3 months, the site you are scraping changes its structure so that your scraper software need to readjust to match the current web structure, that's mean you have to call the programer once again.
Grabby come to overcome that problem, you just need a few click to run the software to scrape the website. and when the site changes its structure again, you just have to re-adjust the Selector with just a few click, no need to call the progamer (you can call me if you're facing problem when doing this, for free).