WhatsApp & SMS Campaign Scheduler

I want a lightweight platform that lets me run marketing campaigns on both WhatsApp and regular SMS without needing to log in every day. The single must-have feature is scheduled messaging, specifically the ability to set up recurring messages (daily, weekly, monthly, or on a custom interval) so my offers and reminders keep going out on autopilot.

The flow I picture is simple: I upload or paste a contact list, craft my promotional copy, choose the recurring pattern, and hit save. From there the system should take over—queueing each batch, handling delivery windows, and giving me a quick status view so I know everything went out. If you can surface basic send logs or a concise dashboard, great; deeper analytics or auto-replies could be added later but aren’t required for this first build.

Key points for the deliverable
• Supports both WhatsApp Business API and standard SMS gateways (Twilio, Nexmo, or any equivalent you recommend)
• Recurring scheduler with flexible intervals and easy pause / edit controls
• Clean, minimal UI that works on desktop and mobile browsers
• Simple CSV import for contacts and an opt-out mechanism to keep us compliant

Please let me know which API or library stack you’d use, the estimated timeline to reach a working MVP with those scheduling capabilities, and any similar messaging tools you’ve built before.