We need an experienced freelancer to complete and stabilize WhatsApp Meta API integration for automated payment due reminders in our gym SaaS product. Stack Backend: NestJS Frontend: React Native Core work is ~90% done; issues are mainly around Meta API testing, templates, and delivery Scope Fix WhatsApp Meta API testing/sandbox issues Validate message templates and webhooks Ensure reliable message delivery from backend Must-have Proven hands-on experience with WhatsApp Meta API (mandatory) Engagement Short-term task with more projects likely after successful delivery Please apply only if you’ve already done WhatsApp Meta API integrations. Please answer these questions in your proposal: 1) Describe a WhatsApp Meta API integration you have already taken to production. Include how you handled WABA setup, template approvals, and webhooks. 2) What are the most common reasons WhatsApp Meta API messages fail during testing or don’t get delivered, and how do you debug them? (Be specific — sandbox vs prod, template status, opt-in, callbacks, etc.) 3) Have you worked with backend-triggered WhatsApp notifications (e.g., payment reminders or transactional messages)? If yes, explain how you ensured reliability and handled retries or failures.