MailChimp is an email marketing service provider that has over 7 million users that collectively send over 10 billion emails through the service each month. It’s a web based application but it also has an offline application with some limited features and all its data can be downloaded. Its subscriber profiles let you to get insight about your subscribers and keep all the contacts in one place. It provides with good automation and personalization as you can set custom rules for sending emails.It even lets the user analyze the behavior and preferences of the subscriber. Mailchimp has a Twitter tailored functionality which allows you to target the Twitter subscribers and allows them to share it with other likeminded people. Its API allows you to sync email marketing with your workflow and also integrates well with most CRM softwares.
The AWeber API uses OAuth to authenticate AWeber users. OAuth provides a standardized way for providing third party applications access to a user's data without the need for that customer to give out their username and password.Email Marketing Automation Tools AWeber