Job Post: Backend Engineer (Traffic Identification & Routing) What We're Building: We need to build a "smart link routing system." In simple terms, it's a system where different people clicking the same short link will see completely different content. Your Main Responsibilities: Manage the "Short Links" (The Bait): Build a service like t.cn or bit.ly for generating and managing short links. The core task is simple: when a user visits a short link, your server tells their browser, "Please redirect to this other address." Develop the Core "Brain" (The Decision Engine): This is the most critical part! You will write a program that, in the split second before redirecting the user, identifies who they are. How? By checking the visitor's information: Check the User-Agent: Identify if the visitor is a search engine crawler (like Googlebot) or a real user on an iPhone or Android. Check the IP Address: Determine if the IP belongs to a datacenter (like AWS, Google Cloud) or is from a known security/virus scanning company. Then what? Based on your analysis, you take different actions: IF it's a crawler or a security scanner -> Show them a harmless, normal page (like a generic image or article). ELSE (if it's a real user) -> Seamlessly redirect them to our intended target page. System Integration & Maintenance: Ensure the "Brain" works reliably with the short link service and third-party platforms (like Google Docs). Maintain and update IP blocklists and crawler signature databases to make the system smarter over time. Skills We're Looking For: Technical Skills: Proficiency in at least one backend language: Python (Preferred), Go, Java, or Node.js. Solid understanding of HTTP protocols (know how 301/302 redirects work inside and out). Experience handling high-concurrency requests to make the "Brain" lightning-fast. Core Competence: Ability to write clean and efficient "if/else" decision-making logic. Know how to parse and utilize User-Agent strings and IP addresses for identification. Experience with caching like Redis is a big plus. Soft Skills: A self-starter who can solve problems independently and enjoys technical challenges. An interest in cybersecurity and the "cat-and-mouse" dynamics of web traffic. Why Join: You'll build a core system that handles complex logic, not just simple CRUD apps. Great technical challenge that will rapidly advance your skills in network protocols, traffic analysis, and high-performance systems. Remote work, flexible hours, and highly competitive pay.