Full-Stack Developer for AI WhatsApp MVP

Project Overview: We are looking for an experienced Full-Stack / Automation Developer to build a Minimum Viable Product (MVP) for a B2B SaaS platform aimed at construction, earthmoving, and agricultural contractors. The system allows field workers (drivers/machinists) to send voice notes or text messages via WhatsApp, which an AI processes into structured data (Daily Work Reports / Invoices / Job Cards) and automatically files into a Web Dashboard for office managers. Core Workflow & Features to Build: Front-End for Field Workers (WhatsApp Integration): Integration with WhatsApp Business API (via Twilio, Green API, or similar). Workers send a voice message (audio) or text describing their work (e.g., "3 hours digging at Client X with 15-ton excavator + 2 tons of sand"). Integration with OpenAI Whisper (Voice-to-Text) and GPT-4o (Structured Data Extraction) to parse: Client Name, Hours, Machine Type, Materials, Location, and Notes. WhatsApp Bot generates a preview PDF and sends it back to the worker with an [Approve / Edit] prompt. Back-End & Web Dashboard (Office Managers): Client Database (CRM): Simple interface to add/manage clients (Name, Address, Email, VAT/Tax ID). PDF / Daily Report Archive: A structured dashboard where all approved daily reports automatically hang under the corresponding Client/Project file. Export / Billing: One-click option to download the generated PDF or export data to JSON/CSV (for future accounting software integration). User Management: Multi-tenant setup so different companies can log into their own isolated environment. Preferred Tech Stack: Messaging & AI: WhatsApp Business API, OpenAI API (Whisper + GPT-4o), Make.com / n8n (or custom Python/Node.js backend). Dashboard / Web App: React / Next.js / Vue.js OR modern No-Code platforms like Bubble.io / FlutterFlow. Database: PostgreSQL, Supabase, or Firebase. To Apply, Please Include: Examples of previous projects involving WhatsApp API and OpenAI/LLM integrations. Your estimated timeline and cost for delivering this MVP. Your preferred tech stack for this project and why. Note: Please type "FRIESLAND" at the top of your proposal so I know you've read the full description.