Cem Levent

At Optade, I work as a full-stack developer on an enterprise platform built around two product lines: a computer-vision analytics suite for physical spaces (store traffic, heatmaps, queue and zone analytics) and a route-optimization & fleet-management system for logistics operations.

What I focus on:

• Backend (NestJS, TypeScript, MongoDB): Develop backend services within a multi-tenant, JWT-secured architecture and use Redis + BullMQ queues to process real-time camera/tracking data and heavy background jobs without blocking the main request flow.
  Route optimization engine (Python/FastAPI): Implemented the core routing algorithms — VRPTW (Vehicle Routing Problem with Time Windows) solved with ALNS (Adaptive Large Neighborhood Search) and Simulated Annealing — including local-search operators, vehicle capacity/driver-hours constraints, and OSRM-based real road distance matrices.
  Frontend (Next.js 14 App Router, React, TypeScript): Build analytics dashboards and operational panels (Recharts/Tremor), interactive map-based route visualization (Leaflet), and high-performance data grids (AG-Grid/RevoGrid) that render thousands of orders and vehicles in the browser without performance lag.
  
  Tech stack: NestJS, Node.js, TypeScript, Python, FastAPI, MongoDB, Redis, BullMQ, AWS S3, Next.js, React, Leaflet, OSRM.

I provide end-to-end web solutions by building scalable backend architectures with Node.js and Laravel, while developing modern, high-performance frontend applications using Next.js, React.js, and TypeScript with a strong focus on User Experience (UX) and Technical SEO.
My work primarily focuses on backend engineering, B2B API ecosystems, payment infrastructures, workflow automation, and enterprise-level system integrations.

Key Responsibilities & Integrations:

• Built secure Virtual POS infrastructure integrating multiple bank systems through a centralized, modular architecture — so onboarding a new bank required no changes to the core payment flow.

• Built end-to-end flight booking integrations (SOAP & REST) unifying real-time search, PNR, reservation, and ticketing into a single reliable flow — bridging legacy SOAP airline APIs with a modern stack.

• Implemented hotel and tourism integrations with dynamic pricing, quota synchronization, and availability management, keeping inventory and pricing consistent across multiple providers.

• Developed KVKK (GDPR-equivalent) compliant OTP verification and double opt-in communication systems via SMS provider integrations, ensuring legal compliance across all user messaging.

• Integrated real-time financial data and exchange-rate synchronization, enabling accurate international pricing with no manual intervention.

• Built scalable backend systems and modern frontend interfaces optimized for maintainability, performance, and operational efficiency.
  
  Tech Stack:
  Node.js, Laravel, PHP, Next.js, React.js, TypeScript, MySQL, PostgreSQL, Redis, Docker

Worked as a backend developer building a two-sided service marketplace that connects customers with service providers (cleaning, driving, security, and more), featuring an end-to-end booking, payment, and dispute-resolution flow.

What I built:

• Escrow-style payment flow with Stripe: Designed a secure booking-to-payout lifecycle where customer payments are held by the platform and released to providers only after the service is confirmed — protecting both sides. Implemented provider onboarding via Stripe and automatic platform commission handling.

• Multi-currency handling: Built exchange-rate logic to take payments in one currency and pay out providers in another, with cached rates to stay within API limits and consistent commission calculation across currencies.

• Real-time communication (Socket.IO): Implemented live booking-based chat with instant message delivery, persistence, and typing indicators, keeping customers and providers connected throughout the service.

• Automated booking lifecycle: Built availability scheduling with recurring time-slot generation, timezone-safe date handling, and a CRON-based auto-confirmation system that finalizes completed services and triggers payouts when a customer doesn't respond in time.

• Clean layered architecture: Structured the backend into routes, controllers, services, and repositories with centralized error handling and secured authentication (short-lived JWT + refresh tokens, verified Stripe webhooks).
  

  Tech Stack: Node.js, Express.js, PostgreSQL, Sequelize, Supabase, Stripe Connect, Socket.IO, JWT

As a software development intern, I designed and built an end-to-end customer support & ticket-management platform from scratch, using a microservices architecture.
The system models a full support-escalation workflow across five roles (customer, support agent, leader, technical employee, admin) — from ticket creation and agent auto-assignment to task delegation on Kanban boards and automatic ticket resolution.

What I built:

• Microservices architecture: Split the system into independent services (API Gateway, Auth, Ticket, Notification), containerized with Docker, each owning its domain and communicating through well-defined boundaries.

• Event-driven communication (Kafka): Decoupled heavy operations — transactional emails, Excel report generation — into Kafka topics, keeping HTTP response times low and preventing service blocking under load.

• High-performance inter-service calls (gRPC): Used gRPC for service-to-service communication (token validation, user lookups, online-agent listings) to avoid HTTP latency on internal calls.

• Real-time live chat (Socket.IO): Built live customer–agent chat with typing indicators, read receipts, and unread-message badges, proxied through the gateway.

• Polyglot backend: Combined Node.js/Express services with a Python/FastAPI service, applying CQRS (command/query separation) to isolate domain logic and keep the codebase scalable.

• Automated workflows: Implemented agent auto-assignment (routing the oldest open ticket to the next available agent), task-driven ticket lifecycle, and full Turkish/English localization across UI, emails, and logs.
  

• Tech Stack: Node.js, Express, Python, FastAPI, MongoDB, Redis, Kafka, gRPC, Socket.IO, Docker, React