Software Engineer, Fullstack – AI Platform

The Role

We are currently seeking a Software Engineer, Fullstack to join the AI Platform team, which powers intelligent experiences across our AI products.                                                                                      

As a Fullstack Engineer, you'll build and ship features across both the backend services and frontend interface of the AI Platform — spanning Python FastAPI/Flask microservices, AWS Lambda, DynamoDB, Redis, WebSocket streaming, and a Svelte-based real-time chat UI. You'll work across the full stack to deliver features for Addison, Addepar's AI-powered assistant. Current capabilities include conversational portfolio analysis, specialized agents for data operations and reporting workflows, dynamic chart generation, and real-time streaming interactions — with new agent capabilities and integrations shipping regularly.

Day to day, you'll be writing backend services, building streaming UIs, and connecting the two — delivering complete features in a team where AI products move fast and your work reaches users directly.

Applicants must have legal authorization to work in the country where this role is based on the first day of employment. Visa sponsorship is not available for this position.

What You’ll Do

• Build and maintain backend services that power AI Platform products, developing in Python or other modern backend languages with emphasis on reliability and maintainability. 
• Build and evolve REST APIs — including request validation, error handling, and clear API contracts between frontend and backend. 
• Work with relational and/or NoSQL data models across systems such as MySQL, PostgreSQL, DynamoDB, and Redis. 
• Build and maintain asynchronous processing flows using queues and worker-based systems.
• Build real-time UI features for conversational interfaces — including chat streaming, incremental rendering, and dynamic layouts. 
• Work with WebSocket pipelines to handle streamed data, retries, and reconnection gracefully. 
• Implement state management for streaming UIs, handling partial data, scroll behavior, and UI correctness over time. 
• Deliver features end-to-end — owning both backend logic and the frontend implementation that consumes it.  
• Write strong automated tests, including unit and integration coverage across both backend (pytest) and frontend (Vitest, Playwright), and contribute to CI-based quality gates.
• Debug production issues across service and UI boundaries using logs, metrics, browser DevTools, and system reasoning.
• Contribute to code reviews, system quality, and engineering standards across the team. 
• Grow your skills in your secondary stack with support from senior engineers and through hands-on feature delivery. 

Who You Are

• Bachelor’s degree in Computer Science, Engineering, or related technical field (or equivalent practical experience).
• At least three years of professional fullstack development experience in a production environment.
• Strong in one area (backend or frontend) with demonstrable, production-level depth — not surface-level familiarity.
• Evident experience in the other area — has shipped real features (not just tutorials or side projects) on the complementary side of the stack, with clear desire to grow there.
• Proficiency in at least one production backend language such as Python, Go, Java, or C++, and the ability to work across a polyglot environment.                                   
• Working knowledge of JavaScript/TypeScript and a modern UI framework (Svelte preferred; React, Angular, or Vue acceptable).                                                        
• Solid software engineering fundamentals — debugging, code quality, testing, and operational awareness.                                                                             
• Experience building and maintaining REST APIs in a production context.                                                                                                             
• Experience with relational databases and/or NoSQL data stores in production systems.                                                                                               
• Understanding of asynchronous processing patterns such as queues, workers, and retry/failure handling.                                                                             
• Proficiency with Docker and familiarity with modern development workflows.                                                                                                         
• Strong testing discipline — unit tests, integration tests, and CI pipelines across backend and/or frontend.                                                                        
• Experience building or operating services on cloud infrastructure in a production context.                                                                                         
• Comfort with browser DevTools for debugging UI issues, understanding async behavior, and basic performance awareness.                                                              
• Strong communication and collaboration skills, with the ability to work effectively across teams.                                                                                  
• Growth mindset — eager to deepen skills on your less-experienced side of the stack through real feature delivery.