Principal Full-Stack Engineer

Job Description: Principal Full-Stack Engineer

Role Overview

We are looking for a Principal Full-Stack Engineer to set the technical direction for Mozark’s AI-native Digital Experience Testing Platform. This is a hands-on technical leadership role. As a Principal you will own architecture across product lines drive engineering excellence partner directly with Product Management DevSecOps and the Agentic AI team and be a force multiplier across the engineering organisation. You will write production code lead the hardest technical problems and shape how Mozark builds - for quality security scale and AI at the core.

Key Responsibilities

• Set and evolve the architecture for full-stack systems across product lines

• Drive cross-cutting technical initiatives - performance scalability high availability (5-9s targets) observability and auto-remediation.

• Lead complex full-stack delivery: design and build services in Python (FastAPI) front-ends in React/React Native real-time pipelines (WebRTC streaming) and data platforms

• Establish secure-by-design patterns in collaboration with DevSecOps - threat modelling secrets management dependency hygiene runtime hardening and supply-chain security.

• Raise the bar on quality - define and enforce SDLC quality gates code review standards automated testing strategy (Playwright k6) and release engineering practices.

• Lead architectural reviews RFCs and design documents; act as a final technical reviewer for high-impact changes.

• Mentor and coach Senior and Staff engineers across product lines; develop the next generation of technical leaders.

• Eliminate single points of failure across SRE and product-critical components through technical design and knowledge distribution.

• Represent engineering in customer regulator and partner conversations when deep technical depth is required.

What We’re Looking For

• 12 years of professional software engineering experience with a meaningful portion spent designing and operating large-scale production systems.

• Track record of leading architecture across multiple services or product lines with measurable impact on scale reliability security or cost.

• Deep hands-on expertise across the full stack - strong backend (Python/Go/Java FastAPI or equivalent) proficient front-end (React React Native or equivalent) and fluent with cloud-native infrastructure (Docker Kubernetes).

• Strong systems fundamentals - distributed systems concurrency storage engines networking security and performance engineering.

• Deep experience with AWS and/or GCP including identity networking multi-region deployment data residency and cost optimisation.

• Demonstrated experience designing multi-tenant SaaS platforms including IAM isolation metering and observability.

• Experience integrating LLMs or agentic workflows into production products - managing prompt design evaluation guardrails latency and cost.

• Strong understanding of secure SDLC DevSecOps and compliance-driven engineering

• Excellent written and verbal communication - able to write crisp design documents lead architecture reviews and explain trade-offs to executive and customer audiences.

• Proven ability to mentor senior engineers influence without authority and lead through technical credibility.

• Nice to have: device-cloud or mobile automation infrastructure WebRTC/real-time media geospatial systems (H3) test orchestration platforms or RUM/observability platforms.

Why Join Us

• Shape the architecture of a category-defining AI-native Digital Experience Testing Platform serving customers across 20 countries in Telco BFSI OTT and Public Sector.

• Direct partnership with the CTO CPO and co-CEOs; high-visibility role with influence on product technology and go-to-market decisions.

• Work at the intersection of agentic AI device-cloud infrastructure network truth engines.