Mohammad S.

I help SaaS and marketplace companies secure user authentication and scale backend systems to support millions of users — without sacrificing uptime, compliance, or speed. 13 years building Tier-0 IAM systems used by 60M+ users. If your platform handles sensitive user data, authentication, or account security — and you need it to scale reliably — that's exactly where I specialize. I'm a Senior Backend Engineer with 13 years of experience, focused exclusively on Identity & Access Management (IAM), authentication systems, and high-throughput microservices. Currently, I build and secure Tier-0 services for a marketplace processing $3.8B+ in annual transactions and serving 60M+ users — with 99.99% uptime. What I bring to your project: Authentication & Authorization — OAuth 2.0, MFA, RBAC, JWT, SSO, SAML, GDPR/DSA-compliant identity systems Scalable Microservices — Java, Spring Boot, Kafka, GraphQL, REST APIs across 40+ production services Cloud Infrastructure — AWS (EC2, RDS, Lambda, DynamoDB), Docker, Kubernetes, PostgreSQL, Redis Performance & Reliability — On-call ownership of 100+ API endpoints, 2-3 weekly production releases, real-time monitoring (Grafana, Thanos) AI-Accelerated Development — Using Claude Code, Cursor AI, and GitHub Copilot to deliver faster without cutting corners on quality Recent results: Built the IAM Core Auditing service and Reputation API now used by OpenAI, AWS, and Webflow integration partners Won a company-wide engineering award for multi-tenancy and performance improvements on high-scale IAM infrastructure Led migration of a monolithic platform to microservices architecture, improving deployability and reducing release risk Why work with me: I don't just write code — I think in terms of system reliability, security posture, and business impact. Whether you need to harden your authentication flow, design a microservices architecture from scratch, or fix a backend that's struggling under scale, I bring senior-level judgment and clear communication (English fluent, daily-driver for 13 years in remote international teams). Let's talk about your project. Send me a message with what you're building and where you're stuck — I'll respond with a clear, honest assessment of scope and approach within 24 hours.