Senior Python Developer

About the Role

As a Senior Python Engineer (Full Stack & AI) at Fulfil, you will design and build next-generation systems that power millions of customer orders and financial transactions for some of the world’s fastest-growing merchants.

Our Python-based platform operates at a significant scale, handling millions of transactions per hour. Your work will directly impact system reliability, scalability, and product innovation.

You’ll collaborate closely with teammates across Canada, the U.S., and India, working in a highly ownership-driven environment that values clean architecture, pragmatic engineering, and thoughtful problem-solving.

Location: Toronto, ON (in-office during onboarding; hybrid 3 days/week in office after)

Type: Full-Time

Expected Start Date: Immediately

What You’ll Do

Own the Full Stack

• Design, build, and maintain end-to-end functionality across our Python-based platform, from backend services to frontend integrations.
• Work within a large, mature codebase while contributing to its long-term evolution and scalability.

Deliver Features at Speed

• Lead the design, development, testing, and deployment of new features that directly support high-growth merchants.
• Balance rapid delivery with long-term maintainability.

Apply AI in Production

• Integrate AI-powered capabilities into Fulfil’s ERP using LLMs (e.g., OpenAI, Anthropic).
• Build intelligent workflows that enhance automation, decision-making, and merchant experience across orders, financials, and operations.

Scale with Confidence

• Design and optimize REST and GraphQL APIs (600+ endpoints), microservices, and background processing pipelines.
• Work with containerized infrastructure (Docker/Kubernetes) to support high availability and zero-downtime deployments.

Champion Code Quality

• Refactor and modernize legacy systems.
• Write well-tested, readable code using pytest.
• Participate in code reviews and architectural discussions to raise the bar across the team.

Build Ecosystem Integrations

• Develop and maintain integrations with major commerce platforms (Shopify, Amazon) and logistics providers (FedEx, DHL).
• Ensure reliable data flows across external systems and Fulfil’s core platform.

What You Bring

• 5+ years of experience, ideally, building applications at scale from scratch.
• Strong experience building large-scale backend systems and microservices using Python.
• Hands-on experience with ORMs (e.g., SQLAlchemy, Django ORM) and relational databases (PostgreSQL preferred).
• Proficiency with distributed systems components such as Celery, Redis, RabbitMQ, and background processing.
• Experience writing automated tests (pytest) and using Git in a collaborative environment.
• Demonstrated ownership—seeing projects through from design to production and ongoing support.

Our Approach to AI

What We Do

• Leverage LLMs (OpenAI API, Claude API) to embed AI-driven capabilities into Fulfil’s ERP, powering natural language interfaces, intelligent automation, and merchant-facing insights (e.g., Fulfil x MCP integrations with Claude).
• Focus on applied AI for commerce operations — integrating models to solve real problems like order management, financial analysis, customer insights, and logistics optimization.

What We Don’t

• We are not a core ML/AI research company — we don’t train or fine-tune foundation models.
• We focus on integrating and productizing AI, rather than building new ML frameworks or developing custom model architectures.

Bonus Points

• Experience scaling systems at a high-growth tech company.
• Familiarity with cloud platforms (Google Cloud, Heroku, etc.).
• Passion for optimizing distributed systems or e-commerce workflows.
• Domain-Focused Product Engineering: Experience building or scaling production software in commerce, logistics, or operations domains (e.g., order management, inventory, fulfillment, WMS) or in FinTech/financial systems (payments, reconciliation, revenue recognition, invoicing).

Why Join Fulfil

• Build systems that power real-world commerce at a global scale.
• Work with a highly skilled, collaborative, and distributed engineering team.
• Competitive compensation, benefits, and growth opportunities aligned with Canadian market standards.

About Fulfil

Fulfil is the modern ERP for commerce. Built to power the fastest-growing eCommerce brands, our platform brings together order management, inventory, accoun…