Developing a cross-platform chat app with built-in moderation is streamlined using Momento, which supports various client SDKs and minimizes development costs while enhancing user flexibility. The app's core feature is a moderated chat API that filters profane messages and images using the bad-words library and Amazon Rekognition, respectively, and translates text into multiple languages via Amazon Translate. This setup allows users to communicate in different languages by subscribing to language-specific topics, with all client-side applications relying on a centralized backend. The chat app supports a range of platforms, including web, iOS, Android, Flutter, Unity, and React Native, each using different SDKs to manage tasks such as obtaining Momento auth tokens, subscribing to topics, and posting messages. The implementation requires minimal server-side code, primarily encapsulated within a Lambda function, and eliminates the need for WebSockets, thereby reducing dependencies and development efforts across platforms.