Comprehensive School Management App

I need a school management application with student, parent, admin, and teacher logins.

The application needs to be accessible on web, iOS, and Android platforms.

User Roles and Capabilities:
- **Student**: View assignments, marks, attendance, fee dues, and notifications
- **Teacher**: View and assign assignments, manage marks, track attendance, and post notifications (e.g., fee dues)
- **Parent**: Monitor child's marks, attendance, assignments, and fee dues notifications
- **Admin**: Oversee all operations and data across the platform

The ideal candidate should have:
- Experience in developing multi-role applications
- Proficiency in mobile and web app development
- Strong database management skills
- Familiarity with user authentication and data security measures

Please share any relevant past work and estimated time for completion.