AI Engineer

Location: São Paulo, Brazil

Department: Engineering

About Arena:

Arena is a Series A company backed by top-tier investors such as CRV, Redpoint and Craft Ventures. Arena offers a unique work environment and the chance to collaborate with diverse teammates across multiple countries, with a culture of ownership (autonomy, growth, and responsibility). 

We are a startup created in Silicon Valley with a mission to build communities for creators, publishers and brands with the power of AI. Companies using Arena include Disney, Reuters, Fox, Red Bull and NFL. We have +2,000 customers in 150 countries, with +50M users having conversations on Arena every month and engaging with our AI Agents.

Arena is also expanding its AI product portfolio with MyAvatar.AI, a multimodal platform that enables users to create intelligent, personalized AI avatars through voice, video, and conversational interfaces.

Sometimes you're stuck in a job that doesn't make sense, building AI features that never make it into production. If you enjoy turning cutting-edge AI into real products, solving complex problems, and seeing your work used by millions of users — then Arena is the company you're looking for.

About the Role:

We’re looking for an AI Engineer to build and scale AI-powered experiences across Arena and MyAvatar.AI.
You’ll work closely with Engineering, Product, and other AI-focused teams to design, implement, evaluate, and improve AI systems that power conversational, voice, and multimodal experiences.

What you will be doing:

• Build and integrate AI-powered features and services into production applications.
• Develop LLM-powered applications using APIs, agents, RAG, tool calling, and structured outputs.
• Design and improve AI pipelines for conversational, voice, and multimodal experiences.
• Evaluate model quality, reliability, latency, and cost, and continuously improve AI performance.
• Build experiments and prototypes, then turn successful approaches into scalable production systems.
• Collaborate with Product and Engineering to translate business and user problems into practical AI solutions. 

Must-Have Experience:

• 2+ years of experience in AI Engineering, Machine Learning Engineering, Software Engineering, or a similar technical role.
• Strong Python programming skills and experience building production software.
• Hands-on experience with LLMs, Generative AI, and AI APIs.
• Experience building applications with RAG, embeddings, vector databases, agents, or tool calling.
• Strong understanding of AI evaluation, prompt engineering, model behavior, and production trade-offs.
• Experience working with APIs, cloud infrastructure, and distributed systems.
• Strong problem-solving skills and ability to move quickly from prototype to production.
• Fluent English.

Nice-to-Have Experience:

• Experience with LangChain and LangGraph for building LLM applications, agents, and AI workflows.
• Experience with Node.js and TypeScript or other backend languages.
• Experience with AWS, serverless architectures, and cloud-native applications.
• Experience with real-time systems, WebSockets, GraphQL, or APIs.
• Experience with MongoDB, PostgreSQL, Redis, or other distributed data systems.

We also have some sweet perks like:

🔥 Be a part of the team in Silicon Valley and join a global team.
💪 A team of exceptional engineers leading the cutting-edge AI Agents.
💶 Competitive salary package & benefits.
⛱️ 4 weeks of paid time-off.
📖 Learning and Development budget.
🚀 Key moment to join Arena in terms of growth and opportunities.
💻 Ability to put your stamp on real-world AI applications that serve millions of users.
📚 Fast-learning environment, entrepreneurial and strong team spirit.
🌍 Multiple nationalities: cosmopolite & multi-cultural mindset.
💆‍♀️ Our people matter, work-life balance is important at Arena.