Full-Stack Developer Needed, Backend development to Fix Dashboard & Payment Gateway Errors

We are looking for an experienced Full-Stack Developer with strong backend expertise to help us troubleshoot and resolve critical errors on our data/business dashboard. The main focus of this project is fixing a payment system error, resolving specific backend bugs, and ensuring smooth overall dashboard functionality. ​If you are a problem-solver who can dive into an existing codebase, debug efficiently, and deploy clean fixes quickly, this role is for you. ​Detailed Scope of Work: ​Payment System Troubleshooting: Investigate and fix a critical error within our dashboard’s payment/billing system gateway to ensure flawless transaction flows. ​Bug Fixing & Error Resolution: Identify and patch existing backend bugs, server-side errors, and API integration bottlenecks. ​Performance Optimization: Ensure the dashboard loads correctly, processes data seamlessly, and handles authentication/webhooks without dropping requests. ​Testing & Deployment: Securely test the fixes in a staging/local environment before pushing them to production. ​Technical Requirements: ​Strong Backend Expertise: Deep understanding of server-side logic, API integrations, and token/OAuth configurations. ​Database Management: Experience querying and managing databases efficiently ( PostgressSQL & MongoDB ). ​Payment Gateway Integration: Prior experience working with international payment gateways (Stripe, PayPal, or similar) and handling webhooks/transaction errors. ​Full-Stack Capability: Ability to navigate frontend code if backend fixes require UI state updates or error-message handling. ​Version Control: Proficient with Git/GitHub for clean code management. ​Soft Skills & Project Details: ​Communication: Fluent in English with the ability to provide brief daily updates on progress. ​Security Mindset: Absolute respect for data privacy and remote access security protocols. ​Availability: Ready to start immediately. This is a short-term, milestone-based contract with the potential for ongoing maintenance work if we like your performance. ​How to Apply: ​Please reply with: ​A brief sentence outlining your experience fixing backend/payment errors. ​What tech stack you specialize in for backend development. ​Your availability to start on this project. ​Include the word "FIXER" at the top of your proposal so we know you read the full description.