Custom E-commerce Development with Medusa.js

Custom E-commerce Development with Medusa.js

You spend a week setting up Medusa.js, but during the first load test, the store crashes with ECONNREFUSED on Redis — sessions aren't cached, TPS drops from 1000 to 100, and API response times soar to 5 seconds. Sound familiar? Without proper configuration of the workflow engine and Redis, a production-ready store is out of reach. We've been through this path 30+ times and know how to avoid these pitfalls.

So, what are the advantages of Medusa.js over out-of-the-box solutions? Shopify takes a 2.9% + $0.30 commission per transaction. Medusa.js charges 0%. You have full control over the stack: PostgreSQL or MySQL, Stripe or CloudPayments, S3 or MinIO. For non-standard catalogs, complex discounts, or B2B pricing tiers, it's the only reasonable choice.

What are the hidden pitfalls of Medusa.js?

First — Redis is mandatory for the workflow engine. Without it, sagas lose state, and when a worker crashes, transactions are lost. In one project, we skipped this step — after the first traffic spike, we lost 15% of orders. Second — custom payment providers. If you don't implement correct webhook handling from the payment gateway, money will be deducted but the order won't appear. Third — version migrations: moving from 1.x to 2.x requires a full module restructuring because the plugin system changed.

Medusa 2.0 documentation: 'Sagas provide a way to coordinate long-running transactions across multiple services with automatic rollback on failure.'

How Medusa.js Solves Scaling Problems

Version 2.x was completely rewritten: modular architecture based on Medusa Modules, IoC container, and a workflow engine with compensations. Now each module (Product, Order, Cart) is an independent package with its own DB schema. When load increases, you can easily replace a module with a custom one or add Redis caching without refactoring adjacent layers.

Medusa 2.x Architecture

┌─────────────────────────────────────────┐ │ Medusa Application │ ├─────────────┬────────────┬──────────────┤ │ HTTP Layer │ Workflows │ Subscribers │ │ (API + MW) │ (Sagas) │ (Events) │ ├─────────────┴────────────┴──────────────┤ │ Module Container │ ├──────────┬──────────┬───────────────────┤ │ Product │ Order │ Cart │ Auth │ │ Module │ Module │ Module │ Module │ ├──────────┴──────────┴─────────┴─────────┤ │ Infrastructure Layer │ │ PostgreSQL + Redis + S3 │ └─────────────────────────────────────────┘ 

Example Workflow: Order with Inventory Reservation

The workflow engine in Medusa 2.x uses the Saga pattern: a chain of steps with compensations. If one step fails, all previous steps are automatically rolled back. For example, when placing an order: first check availability, then reserve the product, then charge the payment. If charging fails, the reservation is canceled. This ensures data consistency without manual error handling.

const validateInventoryStep = createStep( 'validate-inventory', async ({ variantId, quantity }, context) => { const inventoryService = context.container.resolve('inventory'); const available = await inventoryService.retrieveAvailableQuantity(variantId, []); if (available < quantity) { throw new Error(`Insufficient stock: available ${available}, requested ${quantity}`); } return new StepResponse({ available }); } ); const reserveInventoryStep = createStep( 'reserve-inventory', async ({ variantId, quantity, locationId }, context) => { const inventoryService = context.container.resolve('inventory'); const reservation = await inventoryService.createReservationItems([{ inventory_item_id: variantId, location_id: locationId, quantity, }]); return new StepResponse( { reservationId: reservation[0].id }, { reservationId: reservation[0].id } ); }, async ({ reservationId }, context) => { const inventoryService = context.container.resolve('inventory'); await inventoryService.deleteReservationItems([reservationId]); } ); export const customOrderWorkflow = createWorkflow( 'custom-order-workflow', function (input) { const { available } = validateInventoryStep(input); const { reservationId } = reserveInventoryStep(input); return new WorkflowResponse({ reservationId, available }); } ); 

What's Included in Turnkey Development

• Analysis and architecture design.
• Medusa.js setup (module configuration, database, Redis).
• Development of custom modules and workflows (sagas with rollback).
• Integration of payment systems and shipping services.
• Frontend storefront on Next.js (SSR/SSG).
• Writing tests and documentation.
• Deployment (Docker, CI/CD, monitoring).
• Team training and access handover.

We guarantee stability: every solution undergoes code review and load testing. Our experience includes 5+ years of complex e-commerce projects. Upon completion, you receive a store ready for peak loads — processing up to 50,000 orders per day with API response times under 150ms.

Work Process

1. Analytics — study requirements, load, integrations.
2. Design — select modules, design database.
3. Development — implement modules, workflows, APIs.
4. Testing — unit, integration, e2e.
5. Deployment — infrastructure setup, CI/CD.
6. Support — monitoring, optimization, enhancements.

Development Timelines

We estimate each project individually, but typical ranges are:

• Basic store (backend + Next.js frontend): 3 to 4 weeks.
• Store with custom modules and integrations: 8 to 14 weeks.
• Enterprise solution with multi-currency and B2B: 16 to 24 weeks.

In one project, migrating from Shopify to Medusa.js saved the client $30,000 per year in transaction fees — these numbers clearly show the economic efficiency of this approach.

Request a consultation — we'll analyze your project and propose an optimal plan. Contact our engineers for a detailed audit of your architecture.

Official Medusa.js documentation: github.com/medusajs/medusa