Mustafa Culban

Senior Backend / Full-Stack Engineer

I build scalable B2B SaaS platforms with a strong focus on backend architecture, security, and cloud infrastructure. I enjoy owning critical systems end-to-end and turning complex requirements into reliable production software.

8+ years SaaSSecurity-critical systems300K–400K DAU impactAWS + GCPRelocation-ready (Germany)Blue Card eligible

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What I Bring

8+ years building and scaling production-grade SaaS systems
Owner of authentication and messaging platforms used by 300K+ daily users
Enterprise-focused engineer with strong security and scalability background
Comfortable owning systems end-to-end: design → implementation → rollout → iteration

Selected Case Studies

Enterprise-Scale Two-Factor Authentication (2FA)

Designed and implemented a scalable Two-Factor Authentication system serving 300K–400K daily active users across enterprise products.

PHP backend with distributed services
TOTP, backup codes, secure authentication flows
High availability and fault tolerance
Enterprise and consumer user support

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OAuth2-Based SMTP Infrastructure Migration

Led the migration of server-wide SMTP infrastructure to OAuth2-based authentication to comply with modern email provider security standards (Google, Microsoft).

OAuth2 authentication flows
Enterprise admin enforcement and configuration
Multi-product integration
Zero-downtime migration strategy

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Jotform Teams — Multi-Tenant Collaboration Platform

Designed and implemented the core backend architecture for an enterprise-grade collaboration platform with RBAC and data isolation.

Multi-tenant team architecture
Role-based access control (RBAC) system
Ghost user ownership model for data isolation
Centralized permission enforcement

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Senior Engineering Snapshot

Designed systems handling hundreds of thousands of daily users
Led migrations affecting multiple products and enterprise customers
Worked closely with product, security, and infrastructure teams
Strong bias for measurable outcomes, reliability, and maintainability

Technical Focus

Backend

PHP, Node.js, TypeScript, REST APIs, system design

Frontend

React, React Native

Databases

MySQL, PostgreSQL, Redis

Cloud & DevOps

AWS, GCP, CI/CD, Docker

I focus on building systems that companies can trust: secure, scalable, and maintainable over the long term.