Full-Stack Engineer — SaaS Architecture · Multi-Tenancy · Backend Systems

I design and ship production software end-to-end. My current focus is building DentaFlow, a multi-tenant clinic management SaaS I'm architecting and developing solo — from schema-based tenant isolation in PostgreSQL to a Next.js 15 frontend with role-gated dashboards.

I care about the things that make software survive real use: clean data boundaries, reliable async pipelines, auth that doesn't leak, and APIs that don't surprise you.

Role: Founder & Lead Engineer (solo build)

A full SaaS platform for dental clinic chains. Built with correctness and isolation as non-negotiables from day one.

Architecture decisions worth knowing:

• Schema-based multi-tenancy in PostgreSQL via Supabase — each clinic gets isolated data without shared-table row filtering hacks
• Raw SQL over ORM — pg pool + node-pg-migrate for full query control and predictable migrations
• Tenant context propagation via nestjs-cls and AsyncLocalStorage — no tenant ID passed through every function argument
• RabbitMQ with dead-letter exchanges and correlation-ID-based idempotency — async jobs don't silently fail or double-process
• Email-first auth flow — /api/auth/resolve-clinic?email= auto-resolves clinic slug so users never manually enter it; invite links pre-fill registration with ?slug=
• Role system — 5 hardcoded SMALLINT IDs (super_admin → patient) with a sentinel UUID for cross-tenant super admin membership

Stack: NestJS on Fastify · PostgreSQL · Redis · RabbitMQ · Next.js 15 · React Query · Zustand

A production-grade analytics backend built as a portfolio project targeting high-value Upwork contracts.

• FastAPI with asyncpg (raw SQL) on TimescaleDB for time-series event storage
• Sliding-window rate limiter in Redis — per-site, per-IP enforcement
• JWT with refresh token rotation — short-lived access tokens, invalidation on rotation
• Multi-site architecture — one backend instance serving isolated analytics per site
• Nginx reverse proxy with TLS termination
• pytest integration suite covering auth, rate limiting, and ingestion correctness

Stack: FastAPI · TimescaleDB · Redis · asyncpg · Nginx · Docker

Sign-language course platform on shared hosting (cPanel/Apache). Scope included both feature development and full DevOps.

• GitHub Actions CI/CD — separate deploy-stage and deploy-production jobs via rsync over SSH; production only deploys from a clean green stage
• rclone pipeline — automated Google Drive uploads with flock, --min-age, and rclone move to prevent partial-file syncs; error-only logging to keep cron noise down
• PHP video streaming — refactored a monolithic streaming script into gdrive_helper.php; Plyr-based player with fullscreen and persistent controls

Stack: PHP · Zen Cart · GitHub Actions · rclone · Plyr

• Social media feed app — NestJS, Prisma, PostgreSQL, Next.js 14, Cloudinary, Zustand, JWT; full Docker setup
• Faith and Future — Next.js 14 marketing site with Framer Motion animations, Lodash, Tailwind, and full SEO
• Ultinity Gift Shop — WooCommerce on LiteSpeed with custom child theme and performance tuning
• WhatsApp CRM (WaAgentAI) — centralised WhatsApp inbox with agent assignment and AI reply suggestions
• Call analytics platform (CallConnectAI) — auto-transcription, searchable transcripts, and key-insight extraction for customer service teams

• Design multi-tenant SaaS backends — tenancy models, role systems, async pipelines, and the auth flows that tie them together
• Write raw SQL when correctness and performance matter more than ORM convenience
• Build CI/CD pipelines that ship safely — staging gates, environment parity, automated deploys
• Integrate Stripe for recurring billing: subscription lifecycle, webhook handlers, edge cases
• Ship full-stack features from database schema to deployed UI without waiting for handoffs

B.Sc. in Information and Communication Engineering BAUET · CGPA 3.72/4.0 · Been captain of Department's football team

• Portfolio: mdabdulwahab.vercel.app
• LinkedIn: linkedin.com/in/wahabmridul-ice
• Email: abdulwahab22400@gmail.com
• Upwork / Fiverr: Available for contract work