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Zeeshan Rana Muhammad

@rmzeeshan

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Senior full stack engineer building secure, scalable AI SaaS on the MERN stack.

Pakistan

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What I'm looking for

I’m looking to build secure, scalable AI-powered SaaS end to end—multi-tenant, RBAC, real-time experiences, and robust third‑party integrations—working in Agile teams where I can ship fast, improve performance, and evolve LLM/RAG capabilities.

I’m a Senior Full Stack Engineer with 5+ years of experience building scalable, production-grade web applications and AI-powered SaaS platforms. I specialize in the MERN stack (MongoDB, Express.js, React.js, Node.js) and bring deep expertise in multi-tenant architecture, LLM integration, RAG pipelines, and real-time systems.

I’ve delivered secure, high-performance backend systems integrated with third-party APIs including Stripe, Twilio, and OpenAI. In Agile environments with distributed, cross-regional teams, I’ve consistently focused on reliability, observability, and maintainable system design.

In recent work, I architected a multi-tenant marketing automation SaaS platform for AI-driven outbound/inbound call, email, and SMS campaigns. I built Python automation workflows using VAPI SDK and OpenAI API, implemented Twilio webhook-based event handling with retry logic, and managed Stripe subscription lifecycle with secure webhook validation.

I also led end-to-end AI product and platform features—such as a conversational e-commerce shopping agent with OpenAI function calling, a RAG-based AI document assistant with document ingestion, chunking, embedding generation, vector indexing, and tenant-level data isolation. From RBAC and secure authentication to low-latency real-time experiences (SSE/Socket.IO), I build systems that perform under concurrent load and ship faster through CI/CD improvements.

Experience

Work history, roles, and key accomplishments

Current

Senior Full Stack Engineer

Current

Marketing Automation SaaS Platform

Jun 2025 - Present (1 year)

Architected a multi-tenant AI SaaS platform for outbound/inbound call, email, and SMS campaigns using Node.js, TypeScript, and Python. Integrated Twilio and Stripe subscription lifecycle management, implemented tenant-scoped RBAC, and optimized MongoDB-backed async queues for high-throughput campaign execution.

Node TypeScript Python Twilio Stripe RBAC OpenAI API MongoDB

Senior Full Stack Engineer

AI-Powered E-Commerce Platform

Jan 2025 - May 2025 (4 months)

Built a conversational shopping agent using OpenAI function calling for product discovery and personalized recommendations. Developed full-stack chat-to-UI flow, optimized MongoDB data models for real-time performance, and enforced RBAC across inventory and order management modules.

OpenAI Function Calling MongoDB RBAC REST APIs Performance Optimization

Full Stack Engineer

Medical Exam Preparation Platform

Aug 2024 - Dec 2024 (4 months)

Led end-to-end development of a questionnaire engine supporting MCQs, case-based questions, and true/false formats with timed exam simulation, random sequencing, and automatic scoring. Built analytics dashboards, designed scalable hierarchical MongoDB taxonomy, implemented scoped RBAC, and created bulk CSV/JSON ingestion while maintaining low-latency performance under concurrent sessions.

MongoDB RBAC Dashboards Timed Simulations Data Modeling CSV JSON Import Pipelines Performance Tuning REST APIs

Full Stack Engineer

RAG-Based AI Document Assistant

Apr 2023 - Aug 2024 (1 year 4 months)

Built a Retrieval-Augmented Generation (RAG) pipeline covering chunking, embeddings, vector indexing, and semantic retrieval. Delivered a real-time streaming chat experience with React and SSE, added document versioning with on-demand re-indexing, enforced tenant-level data isolation, and improved query performance while streamlining CI/CD deployments.

Vector Search OpenAI API React Server Sent Events (SSE)Tenant Isolation CI CD Document Versioning

Full Stack Engineer

Social Content & Community Platform

Feb 2021 - Mar 2023 (2 years 1 month)

Developed a scalable content feed in React.js using virtualization, memoization, and lazy loading to support high-volume post rendering. Built real-time chat with Socket.IO, added WebRTC-based video calling and live streaming, designed REST APIs with validation and consistent response contracts, and improved backend throughput using async optimizations and connection pooling.

React Socket.IO WebRTC REST APIs MongoDB Virtualization WebSockets