AI Fullstack Engineer (Next.js & LLM)

About the Role

At Blazity, we are a team of React.js and Next.js experts building modern, API-first digital products. We partner with enterprise clients as trusted technology advisors, delivering solutions that span complex web platforms and e-commerce ecosystems.

Recently, we've been expanding our AI capabilities-autonomous agents, AI-driven automation, and LLM-powered workflows-helping companies unlock operational efficiency and innovate at scale. We are looking for an AI Fullstack Engineer who is passionate about the intersection of modern web architecture and generative AI.

Our requirements

Must-have Technical Excellence:

• 4+ years shipping production web apps using Next.js (App Router), TypeScript, and React.

• Solid RSC mental model: Deep understanding of server vs. client boundaries, streaming, and caching (cache, revalidate, tags, Server Actions).

• Proven AI Experience: You have shipped LLM-powered features to real users and worked directly with Anthropic or OpenAI APIs (messages, tool use, streaming).

• Prompt Engineering: Practical experience with XML tags, structured output, and few-shot prompting.

• Token Economics: Understanding of input vs. output pricing, context window management, and prompt caching.

• Agentic Loops: Comfortable with tool calls, stop_reason, and multi-turn orchestration.

• AI Security & Evals: Knowledge of LLM failure modes and hands-on experience writing prompt evals.

• Professional Workflow: Proficient at Claude Code, Git, CI, and code reviews.

Soft Skills & Communication:

• Communication: Ability to express thoughts clearly and practice active listening.

• Collaboration: Effective team player, capable of working across different perspectives and technical backgrounds.

• Adaptability: Thriving in fast-changing environments and managing uncertainty with a proactive mindset.

• Critical Thinking: Ability to evaluate complex information objectively to make better technical and product decisions.

• Ownership: Taking full responsibility for outcomes rather than just "closing tickets."

• Language:

  English at a C1 level (both written and spoken) for seamless collaboration with international clients.

Nice-to-have:

• Experience with Agent SDK or Model Context Protocol (MCP).

• Exposure to Vercel AI SDK or LangGraph.

• Building production-grade RAG systems.

• Familiarity with Claude extended thinking, prompt caching, and Batch APIs.

What You Will Do

• Ship Production Apps: Build scalable web applications using Next.js (App Router) and TypeScript, ensuring high performance and clean architecture.

• Engineer AI Workflows: Develop and orchestrate LLM-powered features using Anthropic and OpenAI APIs, focusing on tool use and streaming.

• Agentic Orchestration: Design autonomous agent loops and multi-turn workflows, knowing when to use a structured pipeline versus a dynamic agent.

• Optimize & Evaluate: Manage token economics (pricing, context windows) and implement prompt evaluations (LLM-as-judge, rule-based) to ensure system reliability.

• Collaborate: Work directly with senior engineers, founders, and client teams to shape AI capabilities from concept to production.

What we offer

• B2B Contract:

  80 - 130 PLN/h + VAT.

• Work Style:

  100% remote work from Poland.

• Vacation:

  29 paid vacation days.

• Health & Sport:

  Private medical insurance (fully covered) and a fully paid sports card.

• Environment: High-impact, hands-on role delivering cutting-edge AI solutions for enterprise-grade clients.

Salary ranges

• B2B Contract:

  80 - 130 PLN/h + VAT

Location

• Work Style:

  100% remote work from Poland