Senior Full-Stack Engineer / Team to Migrate Delphi/uniGUI ERP to Modern Stack (.NET / React)

# Senior Full-Stack Developer / Software Architect for Delphi-to-Web Platform Modernization ## Project Overview We own **SIGECOBPRO**, a comprehensive, production-proven enterprise debt collection management platform. The system supports debt recovery operations, call center workflows, legal collections, payment processing, portfolio management, and financial settlements. The current platform is built with **Delphi/Object Pascal using the uniGUI framework** and **Microsoft SQL Server**. We are seeking an experienced **Full-Stack Developer, Software Architect, or specialized development agency** to lead the modernization and phased migration of the platform to a scalable, maintainable, and secure web-based architecture. The target technology stack will be based on: * **Backend:** C#/.NET 8 or Node.js/NestJS * **Frontend:** React or Vue.js * **Database:** Mysql * **UI Framework:** Tailwind CSS or a comparable modern component framework This is not a basic application rebuild. The platform contains extensive financial, operational, and legal business logic that must be carefully analyzed, documented, migrated, and validated. ## Scope of Work ### 1. Legacy-System Assessment and Architecture * Review the existing Delphi source code, including `.pas` and `.dfm` files. * Analyze the current Microsoft SQL Server database, stored procedures, functions, triggers, and integrations. * Identify and document existing business rules, workflows, dependencies, and technical risks. * Recommend a phased modernization and migration strategy. * Design a modular, secure, and maintainable application architecture. * Define RESTful APIs, service boundaries, authentication, authorization, logging, and error-handling standards. * Help determine whether C#/.NET or Node.js/NestJS is the best backend solution for the platform. ### 2. Backend Development and Business-Logic Migration Migrate and validate complex business processes, including: * Payment allocation and amortization cascades, such as: * Collection fees * Interest * ITBIS tax * Principal balance * Automated account-status transitions, including: * Active * Promise to Pay * Legal * Settled * Other configurable collection stages * Collection-agent commission calculations based on monthly quotas, recovery amounts, and performance rules. * Payment arrangements, settlements, discounts, and account adjustments. * Bulk ETL processes for importing and exporting financial data in CSV, Excel, and TXT formats. * Portfolio and debtor-account management. * Audit trails and transaction histories. * ViciDial and predictive-dialer integrations. * SMS, telephony, and other third-party integrations where applicable. ### 3. Frontend Development Develop a responsive, high-performance web application that includes: * Collection-agent workspaces. * Debtor and account-management screens. * Promise-to-pay tracking. * Payment and settlement workflows. * Legal case-management views. * Supervisor and management dashboards. * Search, filtering, reporting, and data-export functionality. * Role-based access and permissions. * Real-time or near-real-time operational updates where required. * Responsive support for desktop and tablet users. The new interface should improve usability and performance while preserving the functionality users depend on in the legacy platform. ### 4. Database Modernization and Optimization * Maintain compatibility with the existing Microsoft SQL Server database during the migration. * Review and optimize complex queries, stored procedures, indexes, and database relationships. * Identify performance bottlenecks and data-integrity risks. * Recommend schema improvements where appropriate. * Create safe migration scripts and database-versioning procedures. * Preserve historical records and maintain transactional accuracy. ### 5. Testing and Functional-Parity Validation * Create unit, integration, regression, and end-to-end tests. * Build a traceability process that maps legacy functionality to the new implementation. * Validate financial calculations against known production scenarios. * Compare outputs between the legacy and modernized systems. * Document identified discrepancies and their resolutions. * Support user-acceptance testing with operational stakeholders. * Ensure verified functional parity before individual modules are moved into production. ## Expected Deliverables * Legacy-system technical assessment. * Business-rule and workflow documentation. * Recommended target architecture and migration roadmap. * API and database design documentation. * Modern backend and frontend source code. * Automated test suite. * Database migration and deployment scripts. * Technical documentation and setup instructions. * Source-control and CI/CD recommendations. * Phased production deployment and cutover plan. ## Required Qualifications * At least **5 years of professional full-stack development experience**. * Strong experience with one or more of the following: * C# and .NET 8 * Node.js and NestJS * React * Vue.js * Advanced Microsoft SQL Server experience, including: * Complex SQL queries * Stored procedures * Functions and triggers * Query optimization * Indexing * Transaction management * Large-volume data processing * Demonstrated experience modernizing or migrating legacy enterprise applications. * Ability to read and understand **Delphi/Object Pascal** source code and extract undocumented business rules. * Experience designing secure RESTful APIs and modular enterprise applications. * Strong testing, documentation, and technical communication skills. * Ability to work with stakeholders to clarify and validate complex operational requirements. ## Preferred Experience Experience in one or more of the following areas is highly desirable: * Debt collection or accounts-receivable platforms. * Banking, lending, insurance, or financial-management systems. * Payment allocation and amortization logic. * Legal collection workflows. * Call center or predictive-dialer integrations. * ViciDial, Asterisk, Twilio, SMS, or telephony APIs. * High-volume ETL and financial file processing. * Incremental replacement of production legacy systems. * Spanish-language business or technical environments. ## Ideal Candidate The ideal candidate will not simply translate Delphi code into another language. We are looking for someone who can: * Understand and document the existing business logic. * Identify architectural and operational risks. * Recommend practical modernization decisions. * Preserve critical financial behavior and data integrity. * Deliver the migration in controlled, testable phases. * Communicate clearly with both technical and business stakeholders. * Take long-term ownership of the technical direction of the platform. ## Engagement Structure We expect this to be a long-term, phased engagement. The initial phase will focus on: 1. Reviewing the legacy application and database. 2. Documenting the current architecture and critical business rules. 3. Identifying technical risks and dependencies. 4. Proposing the target architecture. 5. Preparing a realistic migration roadmap, timeline, and cost estimate. Successful completion of the assessment phase may lead to responsibility for the full modernization effort. ## How to Apply Please answer each of the following questions in your proposal: 1. Have you previously migrated a Delphi, VB6, WinForms, or similar legacy system to a modern web-based architecture? Please briefly describe the system, your role, and the technologies used. 2. What experience do you have optimizing Microsoft SQL Server databases with complex stored procedures, financial calculations, and large data volumes? 3. How would you identify and document business rules contained within a legacy codebase when complete functional documentation is unavailable? 4. Briefly describe your approach to verifying functional parity during a full or phased system rewrite. 5. Which backend stack would you recommend for this project—C#/.NET 8 or Node.js/NestJS—and why? 6. Are you applying as an individual developer or as an agency? Who would perform the architecture, development, database, and testing work? 7. Please provide examples of comparable enterprise modernization projects, including your specific responsibilities. Proposals that do not address these questions may not be considered.