Senior Full-Stack AI Platform Engineer

Colossus Technologies Group; New York (NY); On-site; USD 140,000 - 190,000; Full time

Job summary

Colossus Technologies Group is seeking a Senior Full Stack Engineer for an AI Platform in New York. You’ll join an early-stage, well-funded team to shape architecture, build across the stack, and develop production AI agents and agentic workflows.

You'll design and implement systems with React, Python, .NET, and PostgreSQL, own features end-to-end, and build LLM-based agents and workflows. This role emphasizes ownership, scalability, and close collaboration with product and design.

Qualifications

• Strong full-stack engineering and architecture experience.
• Hands-on experience with React and backend development.
• Experience building with LLMs and generative AI.
• Understanding of prompt design, RAG, context management, evaluation, and tool use.
• Ideally, experience with agent frameworks such as LangGraph, OpenAI Agents SDK, Claude Agent SDK, Pydantic AI, or similar.
• Comfortable working in an early-stage environment with significant ownership.

Responsibilities

• Design and build scalable full-stack systems across React, Python, .NET, and PostgreSQL.
• Own features and architecture end-to-end.
• Build LLM-based agents and agentic workflows.
• Integrate LLMs, RAG, tool use, and orchestration into production applications.

Skills

React

Python

.NET

PostgreSQL

LLMs

RAG

Agent frameworks

Tool integration

Tools

LangGraph

OpenAI Agents SDK

Claude Agent SDK

Pydantic AI

Job description

Colossus Technologies Group is seeking a Senior Full Stack Engineer for an AI Platform in New York. You’ll join an early-stage, well-funded team to shape architecture, build across the stack, and develop production AI agents and agentic workflows.

You'll design and implement systems with React, Python, .NET, and PostgreSQL, own features end-to-end, and build LLM-based agents and workflows. This role emphasizes ownership, scalability, and close collaboration with product and design.