<p><strong>Overview</strong></p><p>Our client is seeking a <strong>Senior Backend Engineer</strong> with deep expertise in <strong>OAuth 2.0</strong>, <strong>Auth0</strong>, and backend development using <strong>.NET (C#)</strong> and <strong>PHP</strong>. This engineer will help design and implement identity, authorization, and reseller-channel features within a distributed, multi-tenant architecture.</p><p>This is a hands-on development role requiring strong systems-level thinking and experience building secure, scalable, service-oriented systems.</p><p><br></p><p><strong>Key Responsibilities</strong></p><ul><li>Design and implement <strong>OAuth 2.0</strong> authentication/authorization flows.</li><li>Integrate client’s platform with <strong>Auth0</strong> (Okta), including identity provider configuration.</li><li>Develop backend services using <strong>.NET (C#)</strong> and <strong>PHP</strong>.</li><li>Support microservices and distributed systems architecture efforts.</li><li>Model complex <strong>reseller / channel-partner</strong> ecosystems and access patterns.</li><li>Contribute to platform-wide security, API design, and hierarchical access models.</li><li>Assist in implementing white-label, multi-tier, and multi-tenant system features.</li><li>Collaborate with engineering leadership during an accelerated implementation window (Auth0 rollout through April 1).</li></ul>

<p><strong>Top 3 Required Skills</strong></p><ol><li><strong>OAuth 2.0 protocol design & implementation</strong>; strong experience integrating with <strong>Auth0</strong></li><li><strong>Backend development in .NET (C#) and PHP</strong></li><li><strong>Reseller / channel-partner system modeling</strong></li></ol><p><br></p><p><strong>Required Experience</strong></p><ul><li>Senior-level engineering background (backend-focused).</li><li>.NET (C#) and PHP development.</li><li>Microservice and distributed systems design.</li><li>OAuth 2.0 and authentication/authorization architecture.</li><li>API security, token handling, and identity workflows.</li><li>Multi-tenant platform engineering.</li><li>White-label and hierarchical access control patterns.</li><li>Usage-based billing or multi-tier rating systems.</li><li>Systems-level design awareness.</li></ul><p><strong>Nice to Have:</strong></p><ul><li>Auth0/Okta hands-on integration experience</li><li>React or light frontend experience</li><li>Industry experience with <strong>MSP</strong> or <strong>telecom</strong> platforms</li></ul>

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