Senior Medusa.js Developer

About Us
We are building a next-generation, premium marketplace. We are moving beyond the traditional "Buy It Now" model to create a dynamic trading platform that includes a sophisticated "Make an Offer" negotiation engine, a digital wallet system, and a full-service physical consignment and warehousing operation.

This is not a standard e-commerce build. We are creating a complex, multi-sided marketplace with unique business logic, hybrid payment flows, and physical inventory management. We have chosen Medusa.js as our foundational architecture because we need total headless flexibility, robust custom workflows, and native marketplace capabilities.

The Role

We are seeking a Senior Medusa.js Developer to lead the technical architecture and development of the platform. You will be responsible for building the core custom modules that differentiate our business, integrating with third-party services, and ensuring the platform is scalable, secure, and performant.

You will work closely with the founding team to translate complex business requirements into elegant, maintainable Node.js/TypeScript code.

Key Responsibilities & Custom Modules to Build

1. The Offer Engine (State Machine): Build a robust negotiation system allowing buyers to submit offers, sellers to accept/decline/counter, and manage the complex state transitions and time-expirations of these offers using Medusa's Workflows SDK.

2. Digital Wallet & Hybrid Payments: Implement a user wallet system where users can hold funds from sales. Crucially, you must build a custom checkout flow that allows a single transaction to be split between wallet funds and a credit card (via Stripe Connect).

3. Warehousing & Consignment Module: Develop a custom backend module to manage physical inventory. This includes generating unique barcode IDs for incoming stock, tracking storage locations, and managing the "Hold in" logic (where buyers purchase but delay shipping to consolidate orders).

4. Stripe Connect Integration: Architect the complex payment splitting and automated payouts required for a multi-vendor marketplace, ensuring compliance and seamless onboarding for our consignors.

5. Multi-Channel Sync: Build robust integrations to sync our "Buy It Now" inventory with Google Shopping and eBay, ensuring real-time stock updates across all channels.

Required Skills & Experience

• Deep Medusa.js Expertise: Proven experience building complex, custom e-commerce solutions using Medusa.js (v1 or v2). You must understand its core architecture, plugin system, and Workflows SDK.

• Node.js & TypeScript: Expert-level proficiency in backend JavaScript/TypeScript development.

• Marketplace Architecture: Experience building multi-vendor marketplaces, handling split payments, and managing complex user roles.

• Stripe Connect: Deep understanding of Stripe Connect (Custom or Express accounts) for marketplace routing and payouts.

• API Design: Strong experience designing and consuming RESTful and GraphQL APIs.

• Database Management: Proficiency with PostgreSQL and Redis.

Work Setup

• Flexible hours / outcome-focused delivery: We care about what you build, not when you log on.

• Experienced Team: Work with a team running multiple SaaS brands and an established digital agency.

To Apply

Please submit:

1. Your CV or LinkedIn/GitHub profile.

2. Links to any relevant projects, demos, or code (specifically Medusa.js projects if possible).

3. Your answers to the following application questions.

Application Questions (Required)

If the above sounds like you, please apply. Your application will include the following questions:

1. What interests you most about building a complex, multi-sided marketplace?

2. Describe a previous project where you built a custom e-commerce solution or marketplace using Medusa.js. What was the most complex custom module you had to build, and how did you approach it?

3. We require a hybrid payment system where a user can pay for a $1,000 order using $400 from their digital wallet and $600 via credit card. How would you architect this custom checkout flow within Medusa.js and Stripe?

4. We need a robust "Make an Offer" engine with states like Pending, Accepted, Countered, and Expired. How would you leverage Medusa's Workflows SDK or custom services to build this state machine reliably?

5. If you had to deliver an MVP of this platform in 8–10 weeks, what would you prioritise, what would you defer, and what specific Medusa plugins or starters would you leverage to accelerate development?

6. What is your general availability each week?

7. What excites you most about joining a startup team building something new from the ground up?

8. What is your expected salary expectation?

9. Please also let us know why you are the right person, explain your experience, and tell us why we should hire you.