Principal Game Engineer in Montréal

We are looking for a Principal Engineer to take architectural ownership of the agent-readable Shop Builder platform. This is the most senior individual contributor role on the DevX and AI team, and the decisions you make here — which surfaces to expose, which formats to support, which standards to set — will bind the platform for years. You are not a manager, but your influence is org-wide. You define how developers and AI agents interact with Shop Builder's foundational capabilities: UI as Data, custom blocks, themes, data binding, catalog, payments. You are the technical authority on what the platform exposes and how, and you are deeply hands-on with the hardest parts of that work.

About Us: Xsolla is a global payments and commerce platform for the games industry, used by thousands of publishers to monetize, distribute, and operate their titles worldwide. Shop Builder is Xsolla's storefront platform — used by publishers and game developers to launch and operate game shops, from straightforward catalog and webshops to fully custom storefronts built headless on our backend. The DevX and AI team owns the public APIs, documentation, and AI features that give developers — and AI agents — the full surface they need to customize and extend Shop Builder.

Responsibilities:

• Own the technical architecture of the agent-readable Shop Builder platform: which APIs to expose, in what shape, through which surfaces (REST, SDK, MCP, CLI).
• Define the interface contracts that LLMs and developers interact with — React component APIs, custom block schemas, theme tokens, data binding formats — and maintain them with the rigor of a public API.
• Design and lead delivery of the MCP server that allows AI agents to build, deploy, and operate Shop Builder storefronts end-to-end without the editor in the loop.
• Architect the CLI and local development environment: how developers scaffold projects, iterate locally, preview changes, and push to production.
• Define the deploy, versioning, and rollback model for developer-published content — custom blocks, themes, and layouts.
• Design the sandbox and preview environment system so agents and developers can iterate without touching live partner sites.
• Set the documentation standard: written for LLMs and humans as first-class users, maintained from single canonical sources and published to every surface.
• Lead the eval harness architecture: how the team measures whether an LLM-generated block, theme, or layout is correct before it ships.
• Collaborate with Principal/Staff Engineers across payments, auth, live ops, and catalog to pull inbound capabilities into coherent developer-facing surfaces.
• Serve as the technical bar-raiser for the team: define code standards, review critical implementation decisions, and mentor the Tech Lead and engineers.
• Contribute to hiring and define the technical culture of the team from day one.

Qualifications & Skills:

• 10+ years of professional engineering experience, with a demonstrated track record as a Staff or Principal engineer who has shaped platforms, APIs, or developer tooling used by external builders.
• Deep expertise in designing and shipping public APIs and SDKs, including versioning strategy, backwards compatibility, and developer ergonomics.
• Expert-level proficiency in JavaScript/TypeScript and React.
• Hands-on experience building CLI tooling and local developer workflows.
• Solid understanding of the Model Context Protocol (MCP) or equivalent agentic tool-use interfaces.
• Experience building systems at global scale on cloud infrastructure (AWS or GCP).
• Ability to write and reason about LLM-friendly documentation and API surfaces.
• Exceptional technical communication.
• Comfort operating in a greenfield context.

Nice to Have:

• Prior experience in game tech, digital commerce, or storefront platforms.
• Experience building platforms where AI agents are a first-class user.
• Familiarity with Figma's plugin/component API, design token standards, and design-to-code pipelines.
• Contributions to open-source developer tooling, SDK frameworks, or API standards.
• Published technical writing, conference talks, or influential community presence in developer tooling or AI-native development.

Benefits: We are passionate about fostering a supportive environment for our team, so we prioritize the physical, mental, and emotional well-being of our employees and their families through a comprehensive Benefits Program. This includes medical, dental, and vision, PTO, and a personalized career roadmap for each employee.

Equal Employment Opportunity Statement: Xsolla is an equal opportunity employer. We celebrate diversity and are committed to creating an inclusive environment for all employees.