In the last few years a lot of free to use email builders have been published on the web! This is a great news because creating a responsive email that works fine on most email clients is a real PITA.
Here we try to define a basic classification for email template builders, for their Business model and for their Architectural choices.
When you use a free tool it may help to understand what’s the plan to monetize it:
Being the only opensource product, Mosaico has a special position in this categorization: of course we hope to make some money by providing Commercial Support for Mosaico but we mainly opensourced it with the hope to create a community around it.
You will also find plenty of proprietary Email Editors built-in in the platform of most email marketing firms like Mailchimp, CampaignMonitor, BenchmarkEmail and many more.