Senior Full-Stack Developer to Build Custom CRM with WhatsApp & AI

We are a Spanish legal services company with a team of approximately 15 people, and we are looking for a highly experienced developer to build a custom CRM and automation platform for our business. We are NOT looking for a simple website or a basic CRM setup. We want to build a central operational platform that can progressively replace our current systems and automate a significant part of our workflow. Main requirements: • Unified inbox for WhatsApp, email, Instagram and Facebook, accessible by our entire team. • Multiple WhatsApp numbers and automatic assignment of conversations to the person responsible for each client. • CRM for both new leads and existing clients. • Lead management and automated follow-ups. • AI-assisted responses to client messages: AI prepares responses and our team can approve/edit them before sending. • AI classification of simple vs. complex client questions. • AI analysis and summarization of documents, particularly medical records. • AI-assisted lead qualification based on our internal criteria. • Case management with different workflows depending on the type of legal case. • Automatic deadlines, reminders, tasks and alerts. • Centralized document management for every client/case. • Client portal where clients can see the current status of their case and the next steps. • Automated client communications and follow-ups. • Dashboards and business metrics. • User roles, permissions and audit logs. • Future integrations with invoicing, electronic signatures and other legal tools. We already have a detailed 8-page project briefing explaining our current processes, bottlenecks and desired functionality. This will be provided to shortlisted candidates. Important: We do not expect everything to be built at once. We want to develop the platform in phases, starting with the core CRM and unified communications system and then progressively adding automation and AI. We are looking for someone who can not only code, but also recommend the best technical architecture and tell us when an existing technology/API should be used instead of building something unnecessarily from scratch. Experience with WhatsApp Business/Cloud API, Meta APIs, CRM development, AI/LLM integrations, document processing and workflow automation is highly desirable. Ownership is important: the custom code, infrastructure accounts, databases and project documentation should remain under our company’s control so another developer could maintain the system in the future if necessary. Budget: The budget shown in this job post is indicative. After reviewing our complete briefing, please propose the architecture, development phases, estimated timeline and your own fixed price. When applying, please include: 1. Examples of similar CRM/automation platforms you have personally built. 2. Your experience integrating WhatsApp Business API. 3. Your experience implementing AI/LLMs into real business workflows. 4. Whether you would build this yourself or work with a team. 5. A brief explanation of how you would approach a project like this. Please do not send a generic proposal. We are looking for a long-term technical partner if the first phase is successful.