About Replika

Replika is an AI companion loved by 35M+ users around the world. We’re redefining what it means to connect with technology – emotionally, intelligently, and personally. From mobile to VR, we’re building an experience that feels less like software and more like someone who gets you.

We’re scaling fast and taking on bold challenges to become the most human AI on the planet.

About the role

We’re looking for a Senior AI Engineer to design and scale the systems powering Replika’s emotional AI. This is not an infrastructure or ops role – it’s a software engineering role focused on building robust APIs, integrating cutting-edge AI technologies, and delivering systems that scale. You will work directly with the CTO and partner closely with AI researchers and product teams to bring next-generation emotional AI to millions of users.

Responsibilities

• Design and build APIs that deliver real-time emotional AI experiences at scale (sub-second latency for millions of requests).
• Integrate with industry-standard LLMs (OpenAI, Anthropic, LLaMA, Mistral) and vector DBs (Pinecone, Weaviate, Milvus).
• Apply AI developer frameworks such as LangChain, LangFuse, Guardrails AI, and emerging observability tools for LLMs (e.g., Weights & Biases, OpenTelemetry for AI).
• Lead design reviews, set technical direction, and ensure scalability and reliability of applied AI services.
• Collaborate with researchers to productionize models into robust APIs that work at consumer scale.
• Optimize for global growth: high-availability systems, cost-effective API integrations, and scalable embeddings search.
  

Requirements

• 6+ years of professional experience in backend software development (3+ Python required; FastAPI a plus).
• Deep experience with LLM APIs, embeddings, and vector DBs (Pinecone, Weaviate, FAISS, Milvus, etc.).
• Proven experience designing API-driven systems at scale (hundreds of thousands to millions of DAUs).
• Production level experience, and familiarity with AI frameworks such as LangChain, LangFuse, Guardrails, Haystack, or similar.
• Strong software engineering practices: testing, code reviews, performance optimization, API versioning.
• Docker experience (for packaging/deployment).
• Track record of collaborating across product, research, and engineering teams.
• Startup mindset: adaptable, hands-on, ownership-driven, fast execution, focus on what’s important.
• Knowledge of observability/monitoring for AI systems.
  

Nice to Have

• Experience with streaming data or real-time personalization.
• Prior exposure to conversational AI, gaming, or social platforms.
• Scala or other JVM languages.

Why Join Us?

• Be part of a collaborative and innovative team redefining the future of AI companionship.
• Work on projects that directly impact millions of users worldwide.
• Competitive compensation, flexible work arrangements, and opportunities for professional growth.