Experienced OpenCart 3 Developer Needed for Plugin Customization, Security, and Payment Integration

Job Title Senior OpenCart 3 Developer – Multi-Store Architecture, API Integrations, Security Hardening & Ongoing Management Job Description Overview: We are seeking an expert OpenCart 3 developer to finalize, secure, and manage our multi-store e-commerce platform. We are targeting three distinct European markets (UK, DE, and FR) using a multi-domain setup running off a single backend. The ideal candidate must have advanced experience with OpenCart’s multi-store architecture, custom plugin modification (OCMOD), security hardening, and API integrations. This project will begin with implementation, optimization, and bug fixing, moving into a long-term website management and monitoring arrangement. Key Responsibilities: Multi-Domain & Store Setup: Configure and maintain 3 separate domains (.co.uk, .de, .fr) utilizing OpenCart’s native multi-store functionality, mapping them correctly to a single server directory and ensuring accurate regional localization (currencies, languages, tax zones). Fulfillment API Integrations: Integrate Amazon Selling Partner API (SP-API) for Multi-Channel Fulfillment (MCF) to handle automated stock and order syncing. Integrate ShipHero via GraphQL API/webhooks to handle real-time order routing and tracking updates. Trust & Reviews Integration: Implement localized review mechanisms including Trustpilot, Trusted Shops (crucial for Germany), and Google Customer Reviews. Localization of Payments & Shipping: Setup regional payment gateways (Stripe/Mollie/PayPal) and shipping selectors configured explicitly for local preferences: UK: Cards, PayPal, Apple Pay via Royal Mail / DPD. DE: PayPal, SOFORT/Klarna, SEPA via DHL Paket. FR: Cartes Bancaires, PayPal via Colissimo / Mondial Relay. Bug Fixing & Performance Optimization: Troubleshoot and resolve front-end layout issues, checkout bottlenecks (including guest checkout session drop issues), and optimize code/database queries for fast loading times. Security Hardening: Implement immediate security best practices (moving the storage/ directory outside the public root, renaming the admin folder, adjusting file/folder permissions to strict standards, and ensuring SSL/TLS compliance). Constant Monitoring & Management: Set up automated server uptime monitoring, review OpenCart error logs daily, perform scheduled off-site database backups, and maintain server-level security. Requirements: Deep expertise in OpenCart 3.x core code, OCMOD, Twig template engine, PHP, and MySQL. Proven track record connecting OpenCart to third-party ERPs, fulfillment APIs (GraphQL/REST), and payment gateways. Familiarity with server configurations for multi-store domain mapping (Aliases/Addon domains). Deep understanding of web security fundamentals and PCI-DSS basics. Ability to offer reliable turnaround times for critical system errors or server downtime.