Hire the Best Authorize.Net Development Specialists in Karachi, PK

Full Stack .NET Developer | SaaS, ERP, AI & Automation Specialist | API Integrations Expert Are you looking for a senior Full Stack Developer who can architect, build, and scale powerful SaaS platforms, ERP systems, AI-powered tools, and complex integrations using .NET Core and modern frontend frameworks? With 8+ years of hands-on experience, I help startups and businesses turn ideas into secure, scalable, and production-ready applications. What I Specialize In ✔ SaaS Application Development (Multi-Tenant, Subscription Systems) ✔ ERP & Business Management Systems ✔ AI-Integrated Applications & Smart Automation ✔ API Design & Third-Party Integrations ✔ Payment Gateway Integrations (Stripe, PayPal, NMI, Authorize .net, Clear) ✔ Communication Integrations (Twilio, Email, SMS Automation) ✔ Fraud & Risk Tools (Kount, SEON) ✔ Real-Time Systems & Dashboards ✔ Workflow Automation & Backend Architecture ***Tech Stack Expertise*** **Backend** .NET / .NET Core / ASP .NET Core REST APIs & Microservices Entity Framework SQL Server / Database Optimization Authentication & Security Best Practices **Frontend** Angular, React, HTML/CSS Responsive UI / Admin Dashboards Integrations & Tools Stripe, PayPal, NMI, Authorize .net DocuSign API Twilio (SMS / Voice / OTP) Fraud Detection APIs (Kount, SEON, Clear, OnFido, ID Analyzer) Third Party API's (Google, Facebook Graph API, AppStore, Google) Azure(App Services, Azure Functions, Key Vault, Blob Storage, Azure SQL Server, Azure CosmosDB) Plaid-style financial flows Automation & Background Services **Industries I’ve Built Solutions For** Healthcare Systems Fintech Platforms Real Estate Portals eCommerce & Payments Logistics & Rental Platforms Business Automation Tools **What You Can Expect Working With Me** ✔ Architect-level thinking, not just development ✔ Clean, scalable and maintainable code ✔ Business-focused solutions (performance + growth ready) ✔ Strong communication & reliability ✔ Able to handle full lifecycle: planning → development → deployment I’m comfortable working both long-term with growing teams and on focused high-impact projects.

I’m a Top Rated Plus .NET Full Stack Developer with 7+ years of experience designing, developing, and improving secure, scalable, production-ready web applications for startups, SaaS companies, and established businesses. I specialize in ASP.NET Core, C#, React.js, TypeScript, Blazor, SQL Server, PostgreSQL, MySQL, Entity Framework Core, Dapper, and .NET MAUI. I can handle the complete development lifecycle from requirement analysis and software architecture to backend development, frontend implementation, database design, deployment, and ongoing maintenance. .NET Full Stack Development Services * Custom web application development * SaaS platform development * ASP.NET Core and C# backend development * React.js and TypeScript frontend development * REST API and Web API development * Admin dashboards and business applications * SQL Server, PostgreSQL, and MySQL database development * Entity Framework Core and Dapper implementation * Third-party API and payment gateway integrations * Legacy .NET application modernisation * Bug fixing and performance optimisation * Clean Architecture and scalable system design * Blazor web application development * Cross-platform application development with .NET MAUI As an experienced ASP.NET Core Developer and React Developer, I build reliable backend APIs and responsive, user-friendly frontend interfaces that support real business workflows. On the backend, I focus on: * Clean and maintainable C# code * RESTful API development * Authentication and authorisation * Database design and optimisation * Third-party service integrations * Application performance and security * Scalable and modular architecture On the frontend, I develop modern applications using React.js, TypeScript, JavaScript, Blazor, HTML, and CSS, with a strong focus on usability, responsiveness, performance, and maintainability. I help clients: * Turn ideas into complete web applications * Build MVPs and SaaS products * Improve or rebuild existing .NET applications * Fix unstable, slow, or poorly structured systems * Add new features to production applications * Modernise legacy ASP.NET and .NET systems * Integrate APIs, payment gateways, and external platforms * Develop dashboards, portals, and internal business tools What You Can Expect * Strong technical communication and requirement analysis * Clean, readable, and maintainable code * Reliable delivery and regular progress updates * Practical solutions aligned with business goals * Scalable architecture designed for long-term growth * Experience working with existing production codebases Whether you need a .NET Full Stack Developer, ASP.NET Core Developer, C# Developer, React.js Developer, Backend Developer, Frontend Developer, Web API Developer, or SaaS Developer, I can help you design, build, improve, and maintain your application. Send me a message with your project requirements, existing challenges, or product idea, and I’ll help you determine the best technical approach. .NET Full Stack Development | ASP.NET Core | C# | React.js | TypeScript | JavaScript | Web API Development | REST API Integration | Entity Framework Core | SQL Server | Frontend Development | Backend Development | Clean Architecture | SaaS Development | Responsive Web Applications | Database Development | Third-Party API Integration | Performance Optimisation .NET Full Stack Developer | ASP.NET Core Developer | React.js Developer | ASP.NET Core React Developer | C# Full Stack Developer | .NET Core Developer | Full Stack Web Developer | C# Developer | React Full Stack Developer | ASP.NET Web API Developer | .NET Backend Developer | React Frontend Developer | REST API Developer | SQL Server Developer | Entity Framework Core Custom Web Application Development | SaaS Application Development | Full Stack Application Development | ASP.NET Core Web Development | React Web Application Development | Backend API Development | Admin Dashboard Development | Database Development | Third-Party API Integration | Legacy .NET Application Modernisation AI Full-Stack Developer | Generative AI Developer | AI Agent Development | Agentic AI | LLM Integration | AI Copilot Development | AI SaaS Development | AI Workflow Automation | Prompt Engineering | Function Calling | Tool Calling | RAG Development | Vector Databases | Semantic Search | OpenAI API | Claude API | Anthropic | LangChain | LangGraph | Model Context Protocol | MCP | AI Chatbot Development | Natural Language Processing | Intent Recognition | Context Management | Conversation Memory | Structured Outputs | AI Guardrails | LLM Evaluation | AI Debugging | AI Performance Optimization | AI Website Builder | AI Funnel Builder | AI Landing Page Generator | Dynamic UI Generation | Sales Copy Generation | React.js | Next.js | TypeScript | JavaScript | Node.js | Express.js | ASP.NET Core | C# | .NET | REST API Development | WebSocket | PostgreSQL | SQL Server | MongoDB | Redis | Firebase | Azure | AWS | Docker | Microservices | Clean

𝙇𝙚𝙩 𝙢𝙚 𝙩𝙚𝙡𝙡 𝙮𝙤𝙪 𝙬𝙝𝙮 𝙛𝙤𝙪𝙣𝙙𝙚𝙧𝙨 𝙖𝙣𝙙 𝙩𝙚𝙖𝙢𝙨 𝙗𝙧𝙞𝙣𝙜 𝙢𝙚 𝙞𝙣 𝙬𝙝𝙚𝙣 𝙩𝙝𝙚𝙮’𝙧𝙚 𝙗𝙪𝙞𝙡𝙙𝙞𝙣𝙜 𝙎𝙖𝙖𝙎 𝙖𝙣𝙙 𝙈𝙑𝙋𝙨. 🏆 100% Job Success Score ⭐ 1 % Top Rated Plus Freelancer on UPWORK ✅ 15+ Years of Production Experience as a Senior Full Stack Developer ✅ End-to-End Product Ownership & 100+ Websites Delivered As a Senior Full Stack Developer, I’m usually brought in for MVP builds, product rebuilds, and “this is breaking in production” moments. That’s the difference between hiring a Senior Full Stack Developer and hiring someone who only ships features. 𝐖𝐡𝐚𝐭 𝐈 𝐁𝐮𝐢𝐥𝐝 𝐟𝐨𝐫 𝐘𝐨𝐮 𝐀𝐬 𝐚 𝐅𝐮𝐥𝐥 𝐒𝐭𝐚𝐜𝐤 𝐃𝐞𝐯𝐞𝐥𝐨𝐩𝐞𝐫: 𝟏. 𝐒𝐚𝐚𝐒 𝐏𝐥𝐚𝐭𝐟𝐨𝐫𝐦𝐬 & 𝐂𝐮𝐬𝐭𝐨𝐦 𝐂𝐌𝐒 Multi-tenant architecture, PHP & MySQL based custom CMS, custom admin panels, advanced user dashboards, role-based access, and dynamic data charts development. 𝟐. 𝐞𝐂𝐨𝐦𝐦𝐞𝐫𝐜𝐞 𝐒𝐲𝐬𝐭𝐞𝐦𝐬 As a Full Stack Developer, I build custom storefronts, WordPress plugins, WooCommerce plugins, and Shopify setups optimized for conversions and performance. 𝟑. 𝐌𝐜𝐥𝐚𝐬𝐬 𝐕𝐏𝐬 𝐅𝐚𝐬𝐭 Got an idea? I'm a Full Stack Developer who owns the entire stack. I leverage robust frameworks like Laravel, CodeIgniter, and CakePHP to take you from wireframe to deployed product in weeks, not months. 𝟒. 𝐀𝐈-𝐏𝐨𝐰𝐞𝐫𝐞𝐝 𝐖𝐞𝐛 𝐀𝐩𝐩𝐥𝐢𝐜𝐚𝐭𝐢𝐨𝐧𝐬 As a Full Stack Developer working with modern AI tooling, I build advanced AI integrations including ChatGPT and ClaudeAI directly into your product workflows. 𝟓. 𝐀𝐏𝐈 𝐃𝐞𝐯𝐞𝐥𝐨𝐩𝐦𝐞𝐧𝐭 & 𝐓𝐡𝐢𝐫𝐝-𝐏𝐚𝐫𝐭𝐲 𝐈𝐧𝐭𝐞𝐠𝐫𝐚𝐭𝐢𝐨𝐧𝐬 Expert implementation of RESTful architectures and complex third-party systems. I connect everything seamlessly, from secure payment checkouts to enterprise automations. 𝟔. 𝐋𝐞𝐠𝐚𝐜𝐲 𝐒𝐲𝐬𝐭𝐞𝐦 𝐌𝐨𝐝𝐞𝐫𝐧𝐢𝐳𝐚𝐭𝐢𝐨𝐧 Slow, outdated codebase? As a Full Stack Developer, I clean up technical debt and migrate legacy monoliths to scalable structures without breaking live systems. 𝐒𝐞𝐫𝐯𝐢𝐜𝐞𝐬 & 𝐓𝐡𝐢𝐫𝐝-𝐏𝐚𝐫𝐭𝐲 𝐀𝐏𝐈 𝐄𝐱𝐩𝐞𝐫𝐭𝐢𝐬𝐞: ✔ Payments & Billing: Stripe, PayPal, CCAvenue, Authorize.net, MangoPay ✔ Communications & Video: Twilio, Twilio Video Conferencing, Zoom, Jitsi ✔ Marketing & CRM Automation: HubSpot, ConnectWise, MailChimp, SendGrid ✔ Data, Location & Surveys: Qualtrics, TextLocal, ID Analyzer, UPS, Google Maps, Google GeoLocation ✔ Security & Monitoring: JWT, Auth0, Google ReCaptcha, Sentry 𝐓𝐞𝐜𝐡 𝐒𝐭𝐚𝐜𝐤: ➤ 𝐅𝐫𝐨𝐧𝐭𝐞𝐧𝐝 → ReactJS, VueJS, JavaScript, jQuery, Bootstrap, HTML5/CSS3 ➤ 𝐁𝐚𝐜𝐤𝐞𝐧𝐝 → PHP (Laravel, CodeIgniter, CakePHP), NodeJS, Custom MVC ➤ 𝐃𝐚𝐭𝐚𝐛𝐚𝐬𝐞 → MySQL, 𝐀𝐈-𝐏𝐨𝐰𝐞𝐫𝐞𝐝 𝐃𝐞𝐯𝐞𝐥𝐨𝐩𝐦𝐞𝐧𝐭 𝐓𝐨𝐨𝐥𝐬: ➤ Cursor, Cline, GitHub Copilot, Claude Code ➤ ChatGPT, Gemini, v0.dev, Bolt.new ➤ n8n, Zapier, Make (Integromat) ➤ AI Agent Integrations & Workflow Automation 𝐖𝐡𝐲 𝐂𝐥𝐢𝐞𝐧𝐭𝐬 𝐜𝐜𝐜𝐡𝐨𝐨𝐬𝐞 𝐭𝐨 𝐇𝐢𝐫𝐞 𝐌𝐞..? ✅ 𝐅𝐮𝐥𝐥 𝐎𝐰𝐧𝐞𝐫𝐬𝐡𝐢𝐩 - I handle frontend, backend, database, and cloud ✅ 𝐒𝐡𝐢𝐩𝐬 𝐅𝐚𝙨𝐭 - 100+ successful website launches on aggressive timelines ✅ 𝐒𝐜𝐚𝐥𝐞𝐬 𝐖𝐞𝐥𝐥 - Architecture designed for growth and heavy traffic from day one ✅ 𝐂𝐥𝐞𝐚𝐫 𝐂𝐨𝐦𝐦𝐮𝐧𝐢𝐜𝐚𝐭𝐢𝐨𝐧 - Plain English updates, no tech jargon ✅ 𝐒𝐭𝐚𝐲𝐬 𝐀𝐟𝐭𝐞𝐫 𝐋𝐚𝐮𝐧𝐜𝐡 - Available for long-term relationships built on trust and loyalty ✅ 𝐓𝐡𝐢𝐧𝒌𝙨 𝐋𝐢𝗸𝐞 𝐚 𝐅𝐨𝐮𝐧𝐝𝐞𝐫 - I treat your product as a business, not a ticket Please check my UpWork profile, and read other clients' feedback and comments about me. 𝐀𝐕𝐀𝐈𝐋𝐀𝐁𝐋𝐄 𝐅𝐎𝐑 𝐋𝐎𝐍𝐆 𝐓𝐄𝐑𝐌 𝐑𝐄𝐋𝐀𝐓𝐈𝐎𝐍𝐒𝐇𝐈𝐏 𝐖𝐈𝐓𝐇 𝐓𝐑𝐔𝐒𝐓 𝐀𝐍𝐃 𝐋𝐎𝐘𝐀𝐋𝐓𝐘.. Full Stack Developer | PHP Developer | Laravel Developer | CodeIgniter Developer | CakePHP Developer | Senior Web Developer | WordPress Developer | | WooCommerce Developer | Shopify Developer | ReactJS Developer | VueJS Developer | NodeJS Developer | AI Integration Specialist | API Integration Expert | Custom CMS Developer | SaaS Developer | MVP Developer | Backend Developer | Web Application Developer | Frontend Developer | Database Developer | MySQL Expert | Stripe Integration Developer | PayPal Integration Expert | Twilio Developer | AWS Developer | Full Stack Engineer | Senior PHP Developer | PHP Laravel Developer

Senior Full Stack Architect | .NET 8 & Next.js | SaaS, AI & Stripe Billing Architecting enterprise-grade, high-performance web applications and SaaS platforms. With over 7 years of full-stack engineering experience, I specialize in migrating legacy systems to modern frameworks and building secure, multi-currency architectures. HOW I DELIVER VALUE (PROVEN DEPLOYMENTS) I do not just write code; I design scalable systems. I strictly enforce the separation of business logic from the presentation layer to ensure long-term maintainability. ▪ Global B2B eCommerce & Analytics Architected a custom CMS and pricing engine supporting 27 languages. Enabled dynamic multi-currency conversions and global routing using .NET Core and Next.js. ▪ Enterprise Automation & Regression Testing Engineered a comprehensive automation testing solution, migrating legacy QA tools to .NET 8. Integrated physical device testing pipelines using HeadSpin and Selenium to drastically reduce deployment cycles. ▪ AI Proxy & Trade Quoting Architecture Developed the backend infrastructure for an AI-driven contractor application. Integrated Supabase, Twilio, and complex Stripe Connect payment gateways for seamless multi-party transactions. ▪ Social Intelligence & Observability Dashboards Built scalable review aggregation platforms integrating custom data scraping. Implemented OpenTelemetry instrumentation for deep backend monitoring, distributed tracing, and metric sampling. CORE TECHNICAL SCHEMA ► Enterprise Backend: .NET 8, C#, ASP.NET Web API, RESTful Architecture ► High-Performance Frontend: React, Next.js (App Router), TypeScript, WCAG Accessibility ► Cloud & Infrastructure: Azure App Services, Azure DevOps, CI/CD pipelines, Docker, opentelemetry/Otel, Datadog, Signoz ► Databases: SQL Server (Performance Tuning, Stored Procedures), EF Core ► AI & Integrations: Local AI Model Orchestration (DeepSeek, Qwen), Stripe Webhooks, OAuth2 If your project requires robust full-stack architecture built for scale, click "Invite to Job" to discuss your roadmap.

I build scalable, secure, full-stack applications for startups and small-to-medium businesses; from backend APIs to polished, production-ready UIs. As a full stack .NET developer, I specialize in ASP.NET Core Web API development, clean architecture, and modern frontend engineering using React, Angular, and Next.js. Backend Development • ASP.NET Core Web API (.NET 6/7/8) with clean architecture and SOLID principles • RESTful API design, JWT authentication, and role-based access control (RBAC) • Entity Framework Core, PostgreSQL, SQL Server; schema design and query optimization • Multi-tenant SaaS architecture and microservices and PaS projects Frontend Development • React, Next.js (App Router), and Angular for fast, responsive, SEO-friendly interfaces • Component-driven UI development with reusable design systems • State management, API integration, and performance optimization SAP Development • SAP ABAP development and customization • SAP BTP (Business Technology Platform) integration Mobile App Development • Flutter for cross-platform iOS/Android apps • API integration and native-feeling UI/UX for mobile Relevant Project Experience Integrate and maintained modules for DIMO Maint CMMS, a computerized maintenance management system covering asset tracking, work order management, and facility/HVAC maintenance workflows; including data pipelines for asset import, task scheduling, and reporting. Why I'm a Strong Fit for Your Project • I take on a limited number of projects at a time so I can stay fully focused on each one, no juggling, no delayed responses. • Before writing a single line of code, I take time to understand your business goals, not just the technical spec, so the solution I build actually solves the problem you're hiring for. • I treat every project as if I were a long-term part of your team: proactive communication, honest timelines, and flagging risks early rather than letting them surface late. • Whether it's a quick fix, a feature build, or a full application from scratch, you get my complete attention until it's done right. Why work with me: • End-to-end ownership; from database design to deployed, polished UI • Clean, maintainable, well-documented code • Clear communication and reliable delivery on timelines • Experience with Docker, CI/CD, and cloud deployment (Azure/AWS) If you need a dependable full stack developer to build a new application, improve an existing one, or scale your platform; backend, frontend, or both. let's connect and talk about your project.

🧩 About Me I’m a Full Stack .NET Developer and QuickBooks Integration Expert with extensive experience in building robust, high-performance web and desktop applications. I specialize in C#, .NET Core, ASP.NET MVC, and JavaScript frameworks (React, jQuery), combined with deep expertise in QuickBooks Desktop, Online, and POS integrations. ⚙️ What I Offer ✅ QuickBooks Integration & Custom Solutions 🔹Integrations with QuickBooks Desktop, Online, and POS (all versions) 🔹Sync external data sources with QuickBooks (databases, web apps, CRMs, etc.) 🔹Develop custom QuickBooks add-ins and utilities 🔹Web Connector, SDK, and REST API-based integrations 🔹Automated data import/export, invoice sync, and inventory management 🔹Integrations with SharePoint, Google Sheets APIs, Wix, Shopify, Salesforce, WooCommerce, and other third-party systems ✅ .NET Full Stack Development 🔹Web applications using ASP.NET MVC / .NET Core (6, 7, 8, 9) 🔹Backend services and RESTful APIs 🔹Database design and optimization (MS SQL, T-SQL, Dapper, Entity Framework) 🔹Responsive UI using HTML5, CSS, JavaScript, React, jQuery 🔹WinForms and WPF for desktop applications 🔹Integration with third-party APIs and payment gateways ✅ Other Services 🔹System analysis and architecture design 🔹Debugging, testing, and optimization 🔹Technical consulting for scalable software solutions 🧠 Skills Summary ✅ Languages & Frameworks: 🔹C#, 🔹VB.NET 🔹.NET Core, 🔹ASP.NET MVC 🔹Entity Framework 🔹 LINQ ✅ Frontend: 🔹React 🔹jQuery 🔹HTML5, 🔹CSS, 🔹JavaScript ✅ Database: 🔹SQL 🔹Server 🔹SQLite 🔹MySQL 🔹PostgreSQL ✅ QuickBooks: 🔹Desktop (SDK) 🔹Online (API) 🔹POS 🔹Web Connector ✅ Integrations: 🔹SharePoint 🔹Google Sheets 🔹Wix 🔹Shopify 🔹Salesforce 🔹WooCommerce 🔹Payment Gateways Integrations ✅ Other: 🔹REST APIs 🔹WinForms 🔹WPF 💡 Why Choose Me I take pride in delivering clean, maintainable, and performance-driven code. My goal is to help businesses integrate QuickBooks seamlessly or build full-stack .NET applications that solve real-world business problems. If you’re looking for a reliable and detail-oriented developer who understands both QuickBooks ecosystems and enterprise-level .NET development, let’s connect and bring your project to life.