FullStack Engineer

About this role

Senior Full-Stack Engineer — Backend Leaning (Laravel + React) Location: Remote within Europe Preferred locations: Czech Republic, Ukraine, Poland, or the UK Contract rate: Up to $60 USD/hour Core stack: PHP, Laravel, React, Inertia.js About the company Our client builds APIs and developer tools for businesses working with creators. The company is profitable, growing quickly, and developing a unified API that allows customers to integrate with multiple creator and social platforms through consistent responses, webhooks, and SDKs. The engineering team works with high-volume background processing, third-party platforms that can change without warning, and customer data that must remain accurate and reliable. The role We are looking for a senior full-stack engineer with a strong backend focus. You will build and maintain production systems in Laravel and PHP while contributing to customer-facing features in React. This role is best suited to someone who enjoys investigating difficult production problems, building reliable integrations, and taking ownership in a small, highly autonomous team. You do not need to have operated exactly 50 million jobs per day. However, you should be able to explain the systems you have owned, how they failed, and how you measured and improved their limits. What you’ll do Build and maintain production applications using Laravel, PHP, React, and Inertia. Investigate production issues through logs, metrics, request flows, and queue behavior. Design reliable queues, workers, and webhook-delivery systems. Handle retries, duplicate execution, rate limits, backpressure, worker failures, and slow upstream services. Build and maintain integrations with external and sometimes undocumented APIs. Reverse engineer web or API behavior related to authentication, cookies, headers, request signing, rate limits, and other platform controls. Create consistent API behavior across multiple creator and social platforms. Improve database queries, worker capacity