One-Way Messaging App with Admin Panel

I need a custom mobile application with an admin panel for **one-way communication**, similar to WhatsApp broadcast, but fully controlled by admin.
App Requirements (Android + iOS)

Flutter based mobile app (single codebase for Android & iOS)
Firebase backend
Login system (username & password created by admin)
Strictly one-way communication
(users cannot reply, chat, or message anyone)
WhatsApp-style broadcast messaging:

Admin sends one message
Message is delivered individually to users
Push notifications using Firebase Cloud Messaging (FCM)
Each user should see messages in their own inbox


User Segmentation (Unlimited & Flexible)

Admin can create unlimited user segments / categories
Segments can be based on:

* subscription plan
* batch
* course
* custom tags
* Admin can:

* assign one or multiple segments to a user
* modify segments anytime
* Admin can send broadcast messages to:

* one segment
* multiple segments
* or all users

Admin Panel (Web Dashboard)

* Admin login
* Create / edit / delete users
* Assign or change user segments
* Send broadcast messages by segment or individual user
* View message history
Important Conditions

* Simple UI is acceptable (no fancy design needed)
* Firebase project must be created using my email ID
* Source code ownership must be transferred to me
* App must be published on my Google Play Console
(iOS App Store submission can be done after Android)
* 30 days of free bug fixing after final delivery

Timeline & Payment

* Timeline: 20–25days
* Fixed-price project
* Milestone-based payments only
(final payment after successful testing)

Apply only if you have prior experience with **Flutter + Firebase apps and push notifications**.