Senior Python Backend Engineer - Integration Platform

Why Fulfil
Fulfil is a technical founder-led, bootstrapped company in our 11th year of operations. We're a small team of exceptional engineers powering millions of orders for brands like HexClad, Ridge Wallet, and Caraway. No red tape. No product managers. No layers of approval. You'll own critical systems, make architectural decisions, and work directly with merchants — sometimes in their warehouses. You'll ship to production in your first two weeks.

You'll work directly with our Product Support team, who talk to merchants daily. They bring you real problems, you propose solutions, you ship. No PRDs. No one translating customer pain through three layers of abstraction.

At a large company, senior engineers write docs and attend meetings. Here, you'll design systems that process millions of transactions monthly and ship them yourself.

The Team
Integration Platform connects Fulfil to Shopify, Amazon, marketplaces, 3PLs, carriers, and EDI. We process thousands of orders per minute. Mission: integrations are reliable, scalable, debuggable by customers, and fast to build.

A Typical Week

• Monday: Lead design review for re-architecting the integration framework. Goal: reduce time-to-build from weeks to days.
• Tuesday: Build the core framework. Test by migrating an existing carrier integration. Validate it handles 2000 shipments/minute.
• Wednesday: Call with a merchant's technical team. They're setting up EDI with a major retailer. Design the solution together.
• Thursday: Code review for two SDE-IIs on new channel integrations. Guide them on idempotency, retry patterns, rate limiting.
• Friday: Ship the new framework. Watch an SDE-II build a new 3PL integration in 3 days instead of 3 weeks.

What You'll Own

• Order processing architecture: allocation, routing, splitting
• Inventory system reliability at scale
• WMS scalability for high-SKU warehouses
• Technical direction (with Product Lead)
• Mentoring engineers

What We're Looking For

• 4-6 years building backend systems
• Systems that process millions of transactions
• Expert Python, large codebases
• Deep PostgreSQL: partitioning, query planning, performance
• Strong debugging across services
• Clear communication with technical and non-technical people

Tech Stack
Python, PostgreSQL, Redis, Celery, RabbitMQ, SQLAlchemy, Kubernetes, pytest, Claude Code

Hiring Process

• Initial interview — What you've built and owned
• Live coding — Real-time problem solving
• Interview loop — Architecture, system design, bar raiser
• Bootcamp — Even senior engineers start in Product Support to learn how merchants use Fulfil