Web Communication App Development

We are seeking an experienced developer to create an application for enhancing website communication. Instead of sending emails to members, I would prefer to use an app that communicates to the members without doing email. Also, it would notifiy the person on their cellphone that changes are being made. Some of the recipients likely don't want to be informed as they are not involved that deeply. In contrast, some people want to know immediately. So, the app would permit the receiver to turn on or off, VIBRATION and SOUND. Essentially, I want to have an app that instantly communicates to the recipients with text messages. No need to send voice. Can you do this? I don't want to be paying some company to do this. Instead, just use the computer to send the message to the app. The app should provide features such as real-time messaging, notifications, and user management. We want to ensure a seamless integration with our existing website and a user-friendly interface. If you have a solid background in app development and a creative approach to solving communication challenges, we would love to hear from you. Please include your portfolio of similar projects with your proposal. Relevant skills: - App Development - Web Integration - UI/UX Design - Real-time Communication - JavaScript/HTML/CSS