Fullstack Engineer

Matrix Eastern Europe, the offshore division of Matrix IT, one of the leading global R&D services companies with more than 11,000 professionals, is looking for a Fullstack Engineer to join one of our teams – Quack AI!

Quack is building the world’s first operating system for Customer Experience. Their platform blends automation, AI agents, and human insight to help support teams scale smarter — without adding headcount. From real-time QA and co-pilot tools to full-topic AI training, they’re rethinking how companies deliver service at scale.

This role will focus on building the internal tooling and interfaces that power their AI-driven product — used by some of the most forward thinking CX teams in tech. You’ll work closely with Product, AI, and Design to ship features end-to-end, improve UX, and continuously enhance performance and reliability as they scale globally.

Responsibilities

• Build, optimize, and maintain the Quack AI product, including scoring systems, feedback
• loops, review workflows, and dashboards
• Work across the stack using React, TypeScript, Node.js ( Nest JS ), and PostgreSQL
• Collaborate with AI and data teams to surface actionable insights in product
• Own projects from planning to production, including testing, monitoring, and iteration
• Help shape product roadmap and architecture decisions alongside senior team members

Requirements

• 3+ years of experience as a full stack engineer
• Strong skills in JavaScript/TypeScript, React, and Node.js
• Experience working with SQL databases (preferably PostgreSQL)
• Familiarity with APIs (REST or GraphQL)
• A strong sense of product and UX — you care about user impact
• Self-driven, collaborative, and comfortable working in fast-moving teams

Advantages

• Experience building customer support, QA, or analytics tools
• Understanding of how to integrate frontend apps with ML/AI backends
• Worked in early-stage startups or remote-first teams
• Based in or near Belgrade, but open to working from home part of the week

What we can offer

• Remote work and flexible working hours
• Additional 20 days of paid leave
• Professional and career development benefits
• Top-quality work environment
• Online courses
• Online sports activities
• Team buildings and Christmas parties