Migration Specialist for Accounting-Focused ERP

Senior Backend Developer for Custom ERP/Accounting Logic (Re-platforming) ​Project Overview: We have an existing, fully functional internal Institute Management System (Back-office only, no student dashboard). The system has a highly specific, custom double-entry accounting logic (handling 5 layers of money, strict FX rates per transaction, and integer-based currency to avoid decimal rounding). Currently, it runs on a single file with shared storage and fails under concurrent writes. ​The Task: We need an experienced Backend Engineer (Laravel/Node.js + PostgreSQL/MySQL) to migrate this exact business logic to a robust Dedicated Server/VPS architecture. ​Key Requirements: ​Build a relational database that supports concurrent writes with zero data loss (handling serialization and automatic retries). ​Replicate the existing logic: the General Ledger must be derived dynamically from source documents (invoices, payments, sessions), never stored statically. ​Ensure the new backend passes our 33 specific acceptance tests (e.g., matching receivables with invoices, balancing the derived ledger, preventing decimal rounding errors). ​Integrate a provided Payment Gateway API. ​Implement server-enforced role permissions (Admin & Staff only). ​To Apply: Please read the requirements carefully. We will provide a detailed "System Story" document detailing the exact accounting rules to the shortlisted candidates. Provide your fixed-price bid and estimated timeline for a backend re-platforming project of this nature.