Lead Backend Engineer

Join us as a Lead Backend Engineer and help build the backend platform behind one of the fastest-growing AI products in the US market.

We’re looking for a strong backend engineer who enjoys high-load challenges, writes code every day, and likes helping the team make good technical decisions. In this role, you’ll have real technical ownership of our AI Gateway, generative pipelines, and mission-critical backend services powering a product already used by more than 2 million people.

About Us:

Zeely is the agentic AI platform for creating, launching, and scaling paid ads.

Simply put: we've made the best AI solutions and marketing tools available to small and medium businesses — tools that used to be reserved for big brands with expensive marketing teams.

The next big step: a B2B solution for large marketing teams and enterprise clients — workflows, creative analytics, and full control over campaigns across the whole team. For companies where performance marketing already runs at scale and needs more efficiency and automation.

A few numbers that speak for themselves:

• 4 years on the market — a stable, profitable company backed by international investors;

• 6× growth over the past year;

• 2,000,000+ businesses already use Zeely;

• #1 in its category in the US market;

• 200+ specialists on the team;

• Markets: US + worldwide.

Your Key Responsibilities:

• Take technical ownership of a product direction: design and deliver backend solutions for your stream, and make key decisions on scalability, reliability, performance, and system design;

• Help evolve our AI Gateway — the core layer behind text, image, voice, avatar, and video generation across multiple AI models and providers;

• Design and improve AI orchestration pipelines: routing, fallbacks, generation quality, latency, and cost;

• Scale the services you own as traffic and workloads grow;

• Raise engineering quality in your area: code, architecture, security, observability, testing, and operational reliability;

• Work on strategic AI initiatives, including our proprietary RAG pipeline, MCP integrations, and AI agent capabilities;

• Stay hands-on: architecture and design reviews, code reviews, troubleshooting, and technically complex tasks;

• Mentor engineers and share good engineering practices across the team;

• Work closely with Frontend, Mobile, QA, AI Engineering, DevOps, and Product to turn business goals into scalable technical solutions;

• Partner with our Principal Engineer on infrastructure, reliability, and cost optimization for your area.

What We Are Looking For:

• 7+ years of commercial backend development with Node.js;

• 3+ years of hands-on production experience with NestJS;

• Strong system design skills and experience designing and evolving microservice and distributed architectures;

• Experience building and scaling high-load production systems;

• Deep knowledge of PostgreSQL and Redis: performance optimization, data modeling, and caching;

• Experience with ORMs such as Prisma or Drizzle;

• Hands-on AWS experience (for example EKS, RDS, SQS, S3, CloudWatch, OpenSearch);

• Solid knowledge of Docker and containerized environments;

• Good understanding of reliability, observability, monitoring, incident management, and on-call practices;

• Experience leading or mentoring engineers (as a Tech Lead, Team Lead, or a senior engineer who regularly guides others);

• Experience integrating AI APIs (OpenAI, Anthropic, Google, or similar) and working with AI-assisted engineering tools such as Claude Code, GitHub Copilot, or Cursor;

• Ability to balance architecture with hands-on work and pragmatic delivery;

• Upper-Intermediate English or higher.

Why it’s exciting to work with us:

• Take technical ownership of the backend platform behind a rapidly scaling AI product;

• Shape architecture and engineering standards across a strong backend organization;

• Work on real production challenges around high-load systems, AI orchestration, distributed architecture, and infrastructure at scale;

• Build with cutting-edge AI technologies and directly influence how they are integrated into the product;

• Join a strong engineering team with significant autonomy and direct impact on product and technical decisions;

• Remote-first approach: work from anywhere, with the option to visit our offices in Warsaw and Kyiv;

• Regular performance reviews with transparent growth and compensation discussions.

Recruitment process:

Intro Call → Intro with COO & Co-founder → Test Task → Technical Interview → Final Interview → Reference Check → Offer.

Send us your CV — we'd love to get to know you!