Do I always need an OMS?

No. single warehouses and simple rules often fit the shop engine; OMS appears with scale and many sources.

How does this pair with Medusa?

Medusa holds orders; OMS or fulfilment modules extend routing via events and APIs.

Licensed tax rules separate from OMS, otherwise every law change becomes a migration nightmare.

Composable commerce: picking OMS and fulfilment logic - gmi.software

Composable commerce: picking OMS and fulfilment logic

Mikołaj Lehman

CEO & Founder

An OMS chooses fulfilment sources, reserves stock and syncs statuses with carriers and ERP.

When to build custom OMS

Complex cross-border delivery math, split shipments and local customs brokers.

Off-the-shelf OMS licences may hurt at hundreds of thousands of monthly orders.

Front integration

Delivery cost and date must match checkout promises, or complaints spike.

Pre-orders need explicit UI promises.

Edge-case testing

Partial shipments, cancelling one parcel, mid-flight carrier swaps.

Peak simulations with imperfect inventory accuracy.

Frequently asked questions

Do I always need an OMS?: No. single warehouses and simple rules often fit the shop engine; OMS appears with scale and many sources.
How does this pair with Medusa?: Medusa holds orders; OMS or fulfilment modules extend routing via events and APIs.
Cross-border VAT?: Licensed tax rules separate from OMS, otherwise every law change becomes a migration nightmare.

Content updated: March 1, 2026

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An OMS chooses fulfilment sources, reserves stock and syncs statuses with carriers and ERP.

When to build custom OMS

Complex cross-border delivery math, split shipments and local customs brokers.

Off-the-shelf OMS licences may hurt at hundreds of thousands of monthly orders.

Front integration

Delivery cost and date must match checkout promises, or complaints spike.

Pre-orders need explicit UI promises.

Edge-case testing

Partial shipments, cancelling one parcel, mid-flight carrier swaps.

Peak simulations with imperfect inventory accuracy.

Frequently asked questions

Do I always need an OMS?: No. single warehouses and simple rules often fit the shop engine; OMS appears with scale and many sources.
How does this pair with Medusa?: Medusa holds orders; OMS or fulfilment modules extend routing via events and APIs.
Cross-border VAT?: Licensed tax rules separate from OMS, otherwise every law change becomes a migration nightmare.

Content updated: March 1, 2026

Composable commerce: picking OMS and fulfilment logic

When to build custom OMS

Front integration

Edge-case testing

Frequently asked questions

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Composable commerce: picking OMS and fulfilment logic

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Edge-case testing

Frequently asked questions

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Composable commerce: picking OMS and fulfilment logic

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Front integration

Edge-case testing

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Composable commerce: picking OMS and fulfilment logic

When to build custom OMS

Front integration

Edge-case testing

Frequently asked questions

Related articles

MedusaJS + Next.js: B2B storefronts that stay aligned with ERP

Loyalty apps: lifting repeat purchase without spamming users

Let's talk about the project.

Free consultation

Software House in cities

Mobile apps in cities

Let's talk
about the project.

Let's talk
about the project.