Senior BE Developer Node.js Offline

We have a request from our client in the USA. The customer is looking for a BE Developer with 5+ years of commercial experience. 
The client is a U.S.-based digital marketing company that owns and operates a network of 65+ content-driven websites across verticals like sleep, home, auto, legal, and health. Their core focus is organic traffic acquisition (primarily through SEO) and monetization via affiliate partnerships and performance-based advertising. Projects cover the full lifecycle — from content creation and optimization to A/B testing, user behavior tracking, and advertiser integrations.

Requirements for covering scope:
- We're looking for a developer to build a ZIP Allocation API that ingests and enriches U.S. Census ZIP-level data (population, income, urban/rural indicators), applies custom provider allocation logic based on predefined percentages, and outputs validated ZIP-to-partner assignments.
- The solution should include randomization logic, automated QA checks, and manual override capabilities.
- Experience working with public datasets, data transformation, REST APIs, and allocation algorithms is required.
- Familiarity with statistical validation, geo data structures, and ZIP-level segmentation is a plus.
- The developer will be responsible for designing data workflows, implementing the allocation engine, and supporting potential integrations or dashboard views.

We offer:

• Cooperation with a stable company with well-established processes and a positive atmosphere
• Experience in project management of different levels of complexity, methodology, and approaches
• Flexible schedule: Mon-Fri (8 hours a day)
• 18 days of paid vacation; 15 days sick leave
• A decent level of remuneration with regular reviews of the results of cooperation
• Extensive loyalty program