The Rebel Mail Lite API is a low-cost standalone API that allows developers to build complex emails with just JSON. It provides a way to use JSON for rendering fully responsive HTML that works in every email client. It enables you to build emails, find and choose a template, create and update a campaign etc. This includes endpoints and components that relate to templates, campaigns, emails, container, columns, custom-HTML, image and more. Rebel provides a way to make emails interactive while not requiring plug-ins and currently supports SendGrid, Mandrill, SailThru, Mailgun ESPs and more.