At Solstice, we're building AI software that helps life sciences teams turn complex scientific and brand information into marketing content they can create, refine, and review with confidence. Build the foundation for how people work with AI. Your work will span the infrastructure that runs agents and the product experiences that help customers direct, inspect, and use their output.

Take on engineering problems with depth. You'll see your decisions reach customers and use their feedback to improve the product. We're backed by Transformation Capital, Twelve Below, Virtue, and the founders of Datavant, Commure, and Paradigm.

We're opening our first engineering office outside New York, in Toronto, and you'll be one of its first engineers. We cover travel and accommodation. This role will be on-site in Toronto. We'll start remotely for the first few months, with a WeWork stipend for those who prefer it.

As the team grows, we'll move into our own Toronto office by the end of the year and work from there five days a week. We're looking for a Fullstack AI Engineer to build and maintain our agent platform and bring its capabilities into the product. You'll own work across backend services, APIs, agent orchestration, and customer-facing interfaces, with a strong focus on Python and platform engineering.

Python is our primary backend language, and FastAPI powers our APIs. You'll help decide how agents run, recover from failures, access tools and context, and communicate with the application. You'll also build the React and Next.js experiences that give users visibility and control over that work.

You'll partner with product, design, Applied AI, and the broader engineering team to take problems from an initial idea through architecture, implementation, and production.



The scope includes both building new capabilities and making the systems behind them easier to operate and extend. Use Python, FastAPI, Restate, and Redis to build the shared systems that power our agents.

Shape session management, orchestration, tool access, and context delivery so new AI capabilities can build on a dependable foundation.

Build

Python and FastAPI services for content creation, document processing, collaboration, and enterprise integrations. Design explicit API contracts and PostgreSQL data models that make complex workflows straightforward to build on. Give agents current documents, assets, and brand context while keeping customer data and permissions properly scoped.

Bring AI workflows to life in the product. Build with React, Next.js, and TypeScript to show streaming progress and tool activity, support reconnectable sessions, and give users intuitive ways to review, accept, or refine AI output. Make quality measurable.

Partner with Applied AI engineers on evaluations and regression checks, using tools such as Braintrust alongside API and integration tests. Turn production traces and customer feedback into better agent behavior and more dependable releases. Work with product and customer teams to choose the right problems, make practical tradeoffs, and ship complete features.

Deploy, monitor, and improve what you build as customers use it. 5+ years of software engineering experience.



You've built and shipped production software, with experience owning backend services or fullstack applications. ~ Depth in Python and FastAPI. You've shipped and operated production Python services.

You can build well-designed FastAPI APIs and understand asynchronous programming, validation, authentication, and error handling. ~ You design clear service contracts and data models, work comfortably with PostgreSQL and Redis, and think through concurrency, transactions, idempotency, and failure recovery. ~ Experience turning AI into useful software. You've built AI applications or the infrastructure behind them. You're comfortable working in React, Next.js, and TypeScript and connecting an interface to backend APIs.

You care about how the product feels, including usability, accessibility, and performance. ~ You use traces, logs, and metrics to investigate production issues and build instrumentation that helps the next engineer diagnose them. Testing, security, and maintainability are part of how you ship. ~ You work closely with others, seek feedback, and care about whether your work solves the customer's problem.

Experience with Restate or Temporal, sandboxed agent execution, streaming systems, or AI evaluation tools is a plus. Supplemental health, dental, and vision coverage on top of OHIP Equity in an early-stage company, granted on the same schedule as our New York team Your first month in New York, with travel and accommodation covered The base salary range for this role is CAD $155,000 to $230,000, plus equity. We pay at the top of the Toronto market, and we grant equity on the same schedule in every office.

This posting is for an existing vacancy. We can't sponsor work permits for this role at this time. #

📌 Member of Technical Staff - Fullstack AI Engineer (Toronto)
🏢 Solstice
📍 Toronto