Custom Niche Website Builder (PaaS)

I am seeking an elite full-stack developer or development agency to architect and build a high-conversion, niche-specific website builder (PaaS). The platform is inspired by the functionality of SiteSwan but with an aggressive focus on integrated lead generation and automated marketing suites.
The goal is to provide a "business-in-a-box" solution where users can deploy high-converting, mobile-optimized niche sites and immediately fuel them with built-in lead acquisition tools.

Key Deliverables & Scope
1. The Website Builder Engine (Front-End & Back-End)
Drag-and-Drop Editor: A seamless, intuitive UI for users to customize niche-specific templates.
High-Converting Templates: A library of pre-built, mobile-responsive, and SEO-optimized themes tailored to specific industries (e.g., HVAC, law, and real estate).
PaaS Capability: Multi-tenant architecture allowing for user registration, subscription management, and custom domain mapping.
Admin Dashboard: Robust features to manage users, sites, billing, and global template updates.

2. Built-In Lead Generation System
Multi-Source Scraping: Automated capability to pull business data/leads from Google Maps/GMB, social media platforms, and public directories.
Lead CRM: A centralized database where users can manage, tag, and track lead status.

3. Integrated Marketing & Outreach Suite
Social Media: Direct integration for post-scheduling and automated updates.
Email & SMS: Built-in SMTP/Twilio integration for automated cold outreach and lead follow-up sequences.
Conversion Tools: Integrated pop-ups, lead capture forms, and click-to-call functionality.

4. Performance & UI/UX
Extreme Responsiveness: Sites must pass Core Web Vitals with high scores.
Mobile-First Design: Both the builder interface and the generated sites must be flawless on mobile devices.

Technical Requirements
Category
Requirement
Architecture
Multi-tenant SaaS (Software as a Service)
Security
SSL Automation, Data Encryption, Secure Payment Gateways (Stripe/PayPal)
Integrations
Google Maps API, Twilio (SMS), SendGrid/Mailgun (Email), Social Media APIs
Analytics
Built-in visitor tracking and lead conversion metrics


Submission Guidelines for Freelancers
To be considered for this project, please provide:
Portfolio: Examples of previous SaaS or website builder projects (no generic WordPress sites, please).
Tech Stack Proposal: What languages/frameworks do you recommend for the builder engine? (e.g., React/Node.js, Vue, Python, etc.)

Lead Scraping Experience: Briefly explain your experience with data extraction and API compliance.
Estimated Timeline: A rough roadmap from Discovery to MVP.
Note: We are looking for a long-term technical partner. If the MVP is successful, there is an immediate opportunity for ongoing maintenance and feature scaling.