Apart from being a technographic tool for sales and marketing reps, Datanyze has a free chrome extension that extracts email address from the current web window for prospecting purposes.
And if you decide to eventually start a blog
to attract leads for your business, Datanyze can provide a lot of useful enrichment data to help further qualify the prospects coming to your website.
You can also export these new contacts to your CRM, Sheets, or other sales email tools with a single click.
Like mentioned before, the chrome extension is completely free.