Readymade WhatsApp Clone or Custom Build — Messaging App (Mobile + Desktop + Browser)

Job ID: 40592306

Budget: £250 – £750 GBP

We're looking for a developer or team to help us acquire and customise an existing WhatsApp-style chat application to match our specific requirements — rather than building entirely from scratch.
Preferred approach:
We're open to purchasing an existing app/source code (e.g., from marketplaces like CodeCanyon) that already covers most core chat/calling functionality, and having a developer customise it to add our specific requirements below. If no suitable existing solution can be adapted, we're also open to a fully custom build — please indicate which approach you'd recommend and why.
What we need, either way:
1.⁠ ⁠Desktop & Mobile Connection

Users start their computer, open the mobile app, and scan a QR/barcode to connect the desktop app — similar to WhatsApp Web
Android, iOS, and desktop versions required

2.⁠ ⁠User Registration & Accounts

Sign up via email address, with First Name and Last Name
Accounts created under our brand
System auto-generates a unique username and password
Other users only see the full name; users are searchable by unique username once shared

3.⁠ ⁠Key-Based Access System

App launch shows "Enter Key" or "Get Key"
Only Admin can create, issue, and manage access keys
Please advise on best architecture for multi-device key management

4.⁠ ⁠Messaging

Real-time text messaging and file sharing
Only Admin can delete messages/conversations — not regular users

5.⁠ ⁠Calling

App-to-app voice/video calling
Admin controls who can call whom — some users can call each other, others cannot unless granted permission

6.⁠ ⁠Groups

Only Admin can create groups and add/remove members

7.⁠ ⁠Recording & Monitoring

Conversation recording with noise cancellation
Automatic screenshot capture at set intervals
Secure, access-controlled storage for recordings and screenshots

8.⁠ ⁠Notifications

Push notifications and real-time updates

9.⁠ ⁠Deployment

No public App Store/Play Store submission — private/enterprise distribution only (Apple Business/Enterprise Program for iOS, direct APK/private distribution for Android)
SDK/source code access required so we retain full modification rights

How to apply — please include:

Whether you'd recommend buying-and-customising an existing app or building custom, and why
If recommending an existing app: which one, and a link/demo if possible
Your experience with similar projects (messaging apps, admin-permission systems, key-based access, multi-device apps)
Recommended technology stack
Fixed price and realistic timeline (please break down by phase if possible)
Any questions on system design — particularly around key management, QR pairing architecture, or the recording/screenshot implementation

Budget: Open to proposals — please quote based on the scope above.
Timeline: Flexible, but please provide a realistic estimate.
Contract: Freelance, with an NDA and IP protection agreement.