Senior Fullstack Developer (AI Builder)

About the role

We are looking for a Senior Fullstack (AI Builder) to technically lead the end-to-end construction of agents and artificial intelligence solutions at Seazone. You will be responsible for transforming business problems into robust, scalable AI architectures operated in production.

What you will do

• Lead the end-to-end construction of AI agents and solutions, from architecture and model selection to deployment, observability, and iteration in production.
• Establish AI engineering standards, including evaluation strategies, guardrails, cost and latency control, prompt versioning, and quality monitoring.
• Conduct Product Discovery for AI solutions, applying frameworks like Job to be Done to define hypotheses, outcome metrics, and validatable MVPs before scaling engineering.
• Act as a technical peer to the AI Orchestrator and business leaders, understanding processes in depth before automating them and influencing trade-offs between adapting operations and adapting technology.
• Make build vs. buy decisions regarding frameworks, models, and platforms (Claude, OpenAI, agent frameworks, no-code) based on cost, risk, time-to-market, and team capacity.

What we expect from you

• 5+ years of experience in software development, with at least 2 years building and operating solutions with LLMs and agents in production (not just POCs).
• Solid mastery of Python and/or TypeScript/Node.js, with fluency in modern AI patterns: RAG, function/tool calling, multi-step agent orchestration, structured outputs, and streaming.
• Proven track record of agents in production handling real-world failures: hallucinations, quality drift, uncontrolled costs, high latency, or agent loops.
• Product maturity: autonomous ability to conduct Discovery, write hypotheses, define MVPs, measure outcomes, and prioritize based on business impact.
• Strong communication and influence with business areas and leadership, translating business problems into technical architecture and vice versa.
• AI First Mindset: using artificial intelligence as the primary resource to solve problems, optimize tasks, and gain productivity — before resorting to manual processes.

Differentials

• Prior experience technically leading an AI front or squad.
• Deep knowledge of at least one agent framework (Claude Agent SDK, LangGraph, CrewAI) and the ability to justify when to use — and when not to use — each one.
• Experience implementing LLM evaluation strategies (automatic evals, LLM-as-judge, golden datasets) and agent observability (Langfuse, LangSmith, Helicone, or equivalent).
• Background in digital product, growth, sales, or operations with automation.
• Experience in the hospitality, tourism, or marketplace sectors.
• Relevant public contributions: open source, talks, technical articles, or public case studies on AI agents in production.

Incentives

🍽️ Meal allowance - IFOOD in the amount of R$ 462.00;

🩺 Health and Dental plan after 6 months as a PJ (contractor) at Seazone;

🚀 Semi-annual reviews with a growth perspective;

🗣️ Feedback Culture;

🎂 Birthday day-off;

⏸️ Paid maternity/paternity leave;

💰 Referral bonus;

✈️ Discounts on accommodations through our booking site;

🏝️ Accommodation in Florianópolis (SC) for the Seazone anniversary celebration event;

🖥️ Office available for coworking in Florianópolis (SC).

Partnerships

🏋️‍♀️ Partnership with Gympass;

📚 Partnership with Language Schools;

📓Partnership with ACATE - discounts on university tuition, among other benefits;

🧠 Partnership with Conexa Saúde and Psicologia Viva - 24h Telemedicine;

🐾Partnership with Guapeco - Pet Health Plan.

About the hiring process

💼 Contract under the PJ (legal entity) model;

👨‍💻 Remote work;

🌴 Paid rest of 15 days every 6 months of contract.