Selenium vs Ghostlab: What are the differences?
Developers describe Selenium as "Web Browser Automation". Selenium automates browsers. That's it! What you do with that power is entirely up to you. Primarily, it is for automating web applications for testing purposes, but is certainly not limited to just that. Boring web-based administration tasks can (and should!) also be automated as well. On the other hand, Ghostlab is detailed as "Test any website on various browsers and mobile devices simultaneously". It is a Mac based app that allows you to test out your responsive design across a variety of devices and browsers.
Selenium and Ghostlab can be primarily classified as "Browser Testing" tools.
Selenium is an open source tool with 15.3K GitHub stars and 5.07K GitHub forks. Here's a link to Selenium's open source repository on GitHub.