Levi9 is seeking a Senior Software Engineer to design, build, and operate production-grade AI agents and the services around them for a leading Western European media client. You will own features end-to-end—from clarifying business needs and selecting approaches to implementation, evaluation, deployment, monitoring, and continuous improvement—working with backend, frontend, platform, and product teams to apply AI to advertising workflows and business challenges. You will help establish engineering practices for reliable LLM-based systems, including prompt and agent evaluation, security guardrails, observability, and cost-efficient model usage. The technology stack includes TypeScript, Node.js, AWS, Docker, PostgreSQL, React, and related tooling. Requirements include 3+ years of professional software engineering experience with LLM-powered or agentic applications, strong TypeScript and Node.js skills, designing LLM workflows with tool calling and retrieval-augmented generation, REST/OpenAPI integration, secure context propagation, automated testing, cloud/CI/CD, and excellent stakeholder communication. Nice-to-have skills include experience with Mastra, MCP servers/clients, and AI evaluation/observability platforms. This is an on-site role in Kyiv, Ukraine.

Levi9 is seeking a Senior Software Engineer to design, build, and operate production-grade AI agents and the services around them for a leading Western European media client. You will own features end-to-end—from clarifying business needs and selecting approaches to implementation, evaluation, deployment, monitoring, and continuous improvement—working with backend, frontend, platform, and product teams to apply AI to advertising workflows and business challenges. You will help establish engineering practices for reliable LLM-based systems, including prompt and agent evaluation, security guardrails, observability, and cost-efficient model usage. The technology stack includes TypeScript, Node.js, AWS, Docker, PostgreSQL, React, and related tooling. Requirements include 3+ years of professional software engineering experience with LLM-powered or agentic applications, strong TypeScript and Node.js skills, designing LLM workflows with tool calling and retrieval-augmented generation, REST/OpenAPI integration, secure context propagation, automated testing, cloud/CI/CD, and excellent stakeholder communication. Nice-to-have skills include experience with Mastra, MCP servers/clients, and AI evaluation/observability platforms. This is an on-site role in Kyiv, Ukraine.