Principal Software Engineer (React, NestJS, AWS, LLM)

**Company Description**

Sourcico is an international software development company with R&D centers in Macedonia and Serbia. Dedicated to delivering high-quality software solutions, Sourcico combines a talented team of engineers with cost-efficiency and flexibility. By adhering to top industry standards and methodologies, the company focuses on scaling development efforts to meet client needs. Sourcico specializes in providing tailored team extensions and staff augmentation for R&D organizations, ensuring rapid delivery and competitive costs.

Our client's mission is to build the world’s first human-like Agentic AI, or autonomous relationships, that combine friendship, deep game knowledge, and 24/7 availability, giving every High Value Player a trusted partner to play, share, engage with, and grow.

A proactive, emotionally aware AI concierge for every VIP.

- Real-time engagement that drives retention and LTV.
- Handles offers, rewards, and social dynamics intelligently.
- Built for tone, timing, and context. Feels human, acts instant.
- Delivers measurable impact on both revenue and operations.

**Responsibilities**

- End-to-End Feature Ownership
- Take full responsibility for delivering product features from idea to production (design, software development, implementation, testing, deployment, monitoring).
- Collaborate with product/design to define scope, API contracts, and UX flows.
- System & Architecture Design
- Produce High-Level Design documents (HLDs) for complex features, integrations, and system flows.
- Advocate for scalable, maintainable architecture choices from day one.
- Participate in and lead technical discussions, design reviews, and architecture sessions.
- Frontend Engineering (React)
- Build responsive, modern UI with React and TypeScript.
- Implement component architecture, state management, hooks, and performance optimizations.
- Integrate frontend with backend APIs following clean contract definitions.
- Backend Engineering (NestJS)
- Develop REST APIs, micro-modules, authentication flows, and business logic using NestJS.
- Design and document API schemas, DTOs, validation, and error handling.
- Implement integrations with 3rd-party services when needed.
- Database & Data Modeling (PostgreSQL)
- Design normalized data models and schemas that support MVP and future scalability.
- Write efficient SQL queries, migrations, and data-access layers.
- Ensure integrity, indexing strategy, and performance best practices.
- AWS Cloud & DevOps
- Deploy and maintain services on AWS (ECS, Lambda, SQS, CloudWatch, RDS, S3).
- Set up CI/CD pipelines using GitHub Actions.
- Build observable systems with logs, metrics, and monitoring.
- Maintain production-grade cloud architecture with best practices around security, networking,performance, and cost.
- Code Quality, Testing & Documentation
- Write clean, maintainable, well-tested code (unit + integration).
- Create technical documentation, diagrams, and design notes.
- Review PRs and help cultivate excellent engineering standards.
- Communication & Collaboration
- Communicate clearly, proactively, and transparently.
- Discuss design tradeoffs, raise risks early, and push for clarity.
- Give and receive feedback with professionalism and openness.
- Work closely with founders to shape the product roadmap.
- Move fast without compromising essential quality.
- Be flexible in scope and willing to jump into any part of the stack.

**Requirements**

- 7+ years of experience as a full-stack engineer.
- Strong proficiency in React, TypeScript, and modern frontend tooling.
- Strong experience with NestJS and backend design.
- Solid understanding of PostgreSQL, data modeling, and SQL performance.
- Microservices or event-driven architecture knowledge.
- Hands-on experience deploying cloud apps on AWS.
- Strong Git, GitHub and GitHub Actions experience.
- Excellent communication.
- Strong collaboration mindset.
- Open to feedback and design discussions.
- Ability to simplify complexity.
- Proactive, independent, and ownership-driven.
- Product mindset with attention to detail.
- (Nice-to-have) Infrastructure-as-a-code experience.
- (Nice-to-have) Observability tooling familiarity.