While most OSNs today provide some form of privacy controls so that their users can protect their shared content from other users, these controls are typically not sufficiently expressive and/or do not provide fine-grained protection.In this article, we introduce Twitsper, which allows users to have fine-grained control over who sees their messages. Specifically, we demonstrate that such a privacy control can be offered to users of Twitter today without having to wait for Twitter to make changes. We do so by designing and implementing Twitsper as a wrapper around Twitter that enables private group communication while preserving Twitter’s commercial interests. Our design preserves the privacy of group information (i.e., who communicates with whom) both from the Twitsper server as well as from undesired Twitsper users. Our Twitsper client for Android-based devices has been downloaded by over 1000 users and its utility has been noted by several media articles.