Message Function Development for Booking Platform

I need a developer to create a messaging function for my booking website and mobile app.

Key Requirements:
- Messaging between guests and hosts
- Support for text messages only
- Notifications via email, push notifications, and website alerts

Current Tech Stack:
- Java Spring Boot backend
- Next.js (guests), React (hosts/admins) frontends
- PostgreSQL for data, MongoDB for logging
- Flutter for mobile app

Ideal Skills:
- Experience with Java Spring Boot
- Proficient in Next.js and React
- Familiarity with PostgreSQL and MongoDB
- Flutter development knowledge is a plus
- Strong background in implementing messaging systems