Unroll.me is a free online service that lets you easily unsubscribe from email newsletters and other bulk messages in Gmail. You, however, will have to grant complete access to your Gmail mailbox and to your Google Contacts for Unroll.me to automatically remove your email address from various mailing lists. The New York Times reported that Unroll.me is silently scraping your Gmail emails and selling the data to Uber. That prompted me to create Gmail Unsubscriber - it is a free and open-source app that helps you unsubscribe from junk emails with one click. The app is written in Google Apps Script and uses the official Gmail and Google Spreadsheet APIs to detect the bulk emails in your Gmail mailbox. The app runs in your own Google account and you don't have to grant access to anyone so your email data is 100% safe and secure.

Easy to implement

Pros:

Free and respecting your privacy

Cons:

None till now