Principal Engineer — DevX & AI

Xsolla; Montreal (administrative region); On-site; CAD 120,000 - 160,000; Full time

Benefits offered by this job

Medical benefits

Dental benefits

Vision benefits

Paid time off

Career development opportunities

Job summary

Xsolla is seeking a Principal Engineer to own the architecture of the Shop Builder platform in Montreal, Canada. This role involves defining how developers and AI agents interact with the platform, establishing robust API contracts, and designing the server for AI agents. The ideal candidate will have over 10 years of engineering experience, strong proficiency in JavaScript and React, and a deep understanding of API design and cloud infrastructure. Benefits include comprehensive health coverage and a focus on employee well-being.

Qualifications

• 10+ years of professional engineering experience, preferably as a Staff or Principal engineer.
• Expert-level proficiency in JavaScript/TypeScript and React.
• Hands-on experience with CLI tooling and local developer workflows.

Responsibilities

• Own the technical architecture of the Shop Builder platform.
• Define interface contracts between developers and LLMs.
• Design and lead delivery of the MCP server for AI agents.

Skills

JavaScript/TypeScript

React

API design

CLI tooling

Cloud infrastructure (AWS/GCP)

Technical communication

Job description

ABOUT YOU

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. For more information, visit xsolla.com.

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. This is a net-new team of seven, standing up to fill a real gap: no dedicated team has owned the developer surface end to end. That changes now.

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 (Claude Code, Cursor, etc.) 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 (CLI help, dev docs, MCP tool descriptions, AI context).
• 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 — strong opinions about what makes an API delightful vs. painful.
• Expert‑level proficiency in JavaScript/TypeScript and React — the primary interface language for LLMs and developers on this platform.
• Hands‑on experience building CLI tooling and local developer workflows (scaffolding, hot reload, file‑based config, deploy commands).
• Solid understanding of the Model Context Protocol (MCP) or equivalent agentic tool‑use interfaces, and practical experience building tools that AI agents can reliably invoke.
• Experience building systems at global scale on cloud infrastructure (AWS or GCP), with deep knowledge of containerization, CI/CD, and infrastructure‑as‑code.
• Ability to write and reason about LLM‑friendly documentation and API surfaces: you understand that token‑efficiency, predictability, and schema clarity matter as much as human readability.
• Exceptional technical communication: clear RFCs and ADRs, productive architecture reviews, and the ability to explain second‑order consequences to engineering and business leadership.
• Comfort operating in a greenfield context — you define the structure rather than inherit it.

NICE TO HAVE

• Prior experience in game tech, digital commerce, or storefront platforms — understanding the publisher/developer relationship and headless vs. hosted deployment patterns.
• Experience building platforms where AI agents are a first‑class user: MCP servers, LLM tool registries, agent eval pipelines.
• 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.
• Background in block or extension marketplace design: sandboxing third‑party code, schema validation, publisher ecosystems.
• Published technical writing, conference talks, or influential community presence in developer tooling or AI‑native development.

BENEFITS

We prioritize the physical, mental, and emotional well‑being of our employees and their families through a comprehensive benefits program. This includes medical, dental, vision, paid time off, and a personalized career roadmap for each employee. We support professional development through training and educational opportunities to ensure our team thrives both personally and professionally.

EQUAL EMPLOYMENT OPPORTUNITY STATEMENT

Xsolla is an equal opportunity employer. We celebrate diversity and are committed to creating an inclusive environment for all employees. We do not discriminate based on race, color, religion, sex, national origin, age, disability, sexual orientation, gender identity, or any other characteristic protected by law.

We consider qualified applicants with criminal histories in accordance with the Fair Chance Act.

CRIMINAL HISTORY CONSIDERATION

For this role, we will conduct a background check that may include the following:

• Criminal history check
• Employment verification
• Education verification

RELEVANCE TO JOB RESPONSIBILITIES

• Accessing confidential company data
• Ensuring compliance with regulatory requirements
• Handling sensitive financial information / managing budgets / accessing funds

RIGHTS UNDER THE FAIR CHANCE ACT

Applicants are encouraged to inquire about their rights under the Fair Chance Act. If you have questions regarding our hiring practices, please contact [e-mail].