AWeber is an US online service established in 1998 that is the biggest competitor and in the same time an alternative for MailChimp. It provides a ready to use platform to send newsletters and promote your content with unlimited number of subscribers.
It features a drag and drop editor that enables to create easily templates for email, set autoresponders to send emails to new subscribers automatically in order to keep them engaged, use plain text or HTML format, choose ready to use templates, add your logo and many other useful features.
Can convert automatically blog posts into newsletters and send it immediately. View reports and analyze your users, how they interact or which types of templates or emails have more success.
Is able to send emails to entire database or to a segment (part) of a list based on criteria that you choose (location, age, gender etc.).
It supports API.