Senior Python Full Stack Engineer

About Fulfil Fulfil is the modern ERP for commerce. Built to power the fastest-growing eCommerce brands, our platform brings together order management, inventory, accounting, and more, turning complex operations into a strategic advantage.
We’re trusted by brands like HexClad, Ridge Wallet, Caraway, and Resident, and backed by people who want to change the way merchant operations are run. We believe in deep work, radical accountability, and building tools that let sharp people move faster.
About the Role As a 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. Location: Toronto, Ontario (in-office 5 days per week)
Type: Full-Time
Expected Start Date: Immediately
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.
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., 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
Write well-tested, readable code using pytest.
Participate in code reviews and architectural discussions to raise the bar across the team.
Ensure reliable data flows across external systems and Fulfil’s core platform.

5+ years of experience, ideally, building applications at scale from scratch.

• Strong experience building large-scale backend systems and microservices using Python.
• SQLAlchemy, Django ORM) and relational databases (PostgreSQL preferred).
• Experience writing automated tests (pytest) and using Git in a collaborative environment.
• Demonstrated ownership—seeing projects through from design to production and ongoing support.

Bonus Points
Experience scaling systems at a high-growth tech company.
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).

Our Approach to AI
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., Focus on applied AI for commerce operations — integrating models to solve real problems like order management, financial analysis, customer insights, and logistics optimization.
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.
We’re building the ERP that fast-growing eCommerce brands actually want to use, which means we’re taking on entrenched enterprise software with a small, intense team.
Big Tech and VC-backed startups are 400-horsepower engines running at 25% efficiency. They have bloated teams, endless meetings, six months to ship a feature. Everyone ships everyday.
You’ll own meaningful problems with direct customer impact. Our customers run 24/7 operations across time zones, and when they’re launching on BFCM or scaling from $10M to $100M, they need us to move fast. Occasional off-hours calls with our distributed team or for customer launches
You’ll thrive here if: you’re the type who gets energy from building something that matters, want ownership over outcomes vs tasks, are open to receiving regular, direct feedback in public Slack channels from multiple people, and like moving fast without red tape.
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