Full Stack AI Engineer

Kaizen Soft Solutions; New York (NY); On-site; USD 140,000 - 210,000; Full time

Job summary

Kaizen Soft Solutions is seeking a hands-on Full Stack AI Engineer to build AI-native products from the ground up. You will collaborate with founders to turn ideas into production-ready applications and shape the company’s technical foundation.

The role spans frontend, backend, infrastructure, and AI systems. Ideal candidates thrive in fast-moving startup environments, adapt to changing requirements, and own their work end-to-end.

Qualifications

• 4+ years of professional software engineering experience
• Experience building and launching a product from zero to one
• Strong frontend and backend development experience
• Strong skills in TypeScript, JavaScript, React, and Next.js
• Backend experience with Node.js, Python, FastAPI, Go or similar
• Experience with PostgreSQL, APIs, cloud infrastructure, and production deployments
• Hands-on experience integrating large language models into production apps
• Experience with AI agents, RAG, tool calling, embeddings, multimodal AI, or voice AI
• Strong product judgment and ability to operate with limited direction
• Ability to move quickly while maintaining high engineering standards
• Must be actively hands-on and writing production code

Responsibilities

• Build, test, launch, and improve full-stack products from zero to one
• Develop modern frontend applications using React, Next.js, or similar technologies
• Build backend services, APIs, databases, and third-party integrations
• Create AI-powered features using large language models and multimodal models
• Build AI agents that can use tools, complete workflows, and interact with external systems
• Develop retrieval-augmented generation, embeddings, vector search, and knowledge systems
• Integrate voice AI, speech-to-text, text-to-speech, or real-time conversational systems
• Implement structured outputs, tool calling, model routing, and human approval workflows
• Build evaluation, monitoring, and testing systems for AI performance
• Improve application reliability, scalability, security, latency, and AI inference costs
• Work directly with founders, users, and product stakeholders
• Help make product, architecture, and technology decisions

Job description

Position: Full Stack AI EngineerLocation: San Francisco, CA & New York City, NY - OnsiteDuration: Full TimeExperience: 8+ years

Candidate Requirement:

• Candidate must have prior experience working at an early-stage startup.
• Candidate should have strong full-stack experience across frontend, backend, databases, APIs, cloud infrastructure, and production deployments.
• Candidate must have practical experience building AI-powered products. API experimentation, personal projects, coursework, or basic chatbot integrations alone will not qualify.
• Strong candidates will have experience with AI agents, LLM integrations, RAG, model tool calling, multimodal AI, voice AI, evaluations, or real-time AI systems.

About The Role

Our client is looking for a highly hands-on engineer who can help build and launch AI-native products from the ground up. You will work closely with the founders to turn ideas into production-ready applications and help shape the company’s technical foundation.

The right candidate is comfortable working across frontend, backend, infrastructure, and AI systems. You should enjoy fast-moving startup environments, changing requirements, rapid iteration, and taking complete ownership of what you build.

Responsibilities

• Build, test, launch, and improve full-stack products from zero to one
• Develop modern frontend applications using React, Next.js, or similar technologies
• Build backend services, APIs, databases, and third-party integrations
• Create AI-powered features using large language models and multimodal models
• Build AI agents that can use tools, complete workflows, and interact with external systems
• Develop retrieval-augmented generation, embeddings, vector search, and knowledge systems
• Integrate voice AI, speech-to-text, text-to-speech, or real-time conversational systems
• Implement structured outputs, tool calling, model routing, and human approval workflows
• Build evaluation, monitoring, and testing systems for AI performance
• Improve application reliability, scalability, security, latency, and AI inference costs
• Work directly with founders, users, and product stakeholders
• Help make product, architecture, and technology decisions

Qualifications

• 4 or more years of professional software engineering experience
• Proven experience building and launching a product from zero to one
• Prior experience working at an early-stage startup
• Strong experience across frontend and backend development
• Strong skills in TypeScript, JavaScript, React, and Next.js
• Backend experience with Node.js, Python, FastAPI, Go, or similar technologies
• Experience with PostgreSQL, APIs, cloud infrastructure, and production deployments
• Hands-on experience integrating large language models into production applications
• Experience with AI agents, RAG, tool calling, embeddings, multimodal AI, or voice AI
• Strong product judgment and the ability to operate with limited direction
• Ability to move quickly while maintaining high engineering standards
• Must be actively hands-on and writing production code

Preferred Experience

• OpenAI, Anthropic, Gemini, or open-source AI models
• Model Context Protocol and agent orchestration frameworks
• Lang Graph, Llama Index, Vercel AI SDK, or similar tools
• Vector databases such as Pinecone, Qdrant, Weaviate, or pgvector
• Voice AI, WebSocket's, WebRTC, or real-time streaming systems
• AI evaluations, observability, prompt injection protection, and model security
• Docker, AWS, Google Cloud, Azure, or serverless infrastructure
• Experience as an early, founding, or first engineering hire