B2B e-Commerce ERP Integration: Vendor-Built vs Middleware

B2B e-commerce ERP integration is the process of synchronizing critical business data between your wholesale e-commerce platform and your ERP system. This data includes customers, products, pricing, inventory, orders, invoices, payments, and often historical transaction data. Do this integration correctly and your brand has a single operational truth across systems. But done poorly? That creates a ton of manual work, reporting gaps, and downstream customer issues.

For wholesale brands selling into specialty retailers, getting this integration right isn’t optional - it’s a critical part of your operational backbone.

But not all integrations are built the same. The architecture behind them matters more than most brands realize.

What Is B2B e-Commerce ERP Integration?

In layman’s terms, a B2B ERP integration connects your e-commerce system to your ERP so that data moves automatically between the two.

This data commonly includes things like:

• Customer records
• Product catalogs and metadata
• Inventory availability
• Sales orders
• Order history
• Invoices
• Payments

Inside your wholesale B2B however, the complexity of the data increases. Retailers often have negotiated pricing, custom assortments, prebooks, terms-based payments, and historical purchasing patterns that influence future orders.

The integration to handle this complex data is not a simple “cart checkout to accounting” sync. It is a system-level relationship.

Why B2B System Integration Is More Complex In Wholesale

Wholesale B2B has operational nuances that many integration approaches underestimate.

Unlike direct-to-consumer e-commerce, wholesale brands must manage:

• Order history visibility for retailers
• Complex product metadata (size scales, color matrices, seasonal attributes)
• Prebooks and future-dated inventory
• Terms-based invoicing
• Partial shipments and backorders
  

If your integration only moves basic customer and order data, teams quickly fall back to spreadsheets or manual ERP entry to fill the gaps.

That defeats the purpose of integrating your ERP with your B2B.

A wholesale B2B integration must reflect how specialty retail actually works, not how a generic e-commerce flow works.

Two Integration Models: Vendor-Built vs Middleware

There are generally two ways brands connect their ERP to a B2B e-commerce platform - vendor-built integrations, or middleware.

What Is Middleware?

Middleware, often delivered as an iPaaS (integration platform as a service), acts as the connecting layer between systems. It sits between your ERP and your e-commerce platform, syncing data back and forth between them.

A few examples of a middleware platform include Celigo, Boomi, MuleSoft, and Patchworks.

For some brands, middleware has legitimate use cases.

For example:

• Connecting standardized SaaS tools like CRM to email marketing platforms
• Linking systems in industries with predictable, simple transaction models
• Bridging temporary system gaps during migrations

In industries where workflows are relatively standardized and data models are straightforward, middleware can work well. It allows companies to connect multiple tools without each vendor building native integrations for every possible software combination.

The key idea is flexibility, but that flexibility comes with trade-offs.

What Is A Vendor-Built Integration?

A vendor-built integration is developed and maintained directly by the e-commerce platform provider. Instead of inserting a third party between systems, the platform builds a direct connection to the ERP.

This can be API-based (this is how Envoy connects to NetSuite) or file-based and tailored to a specific brand (as with more customized ERPs like SAP).

The advantage you gain here is ownership, which leads to a more needs-targeted solution instead of a generalized approach. A vendor understands both the application logic of their platform and how it should behave within the ERP environment, and will build their integration accordingly.

The trade-off is that it requires deeper engineering investment from the platform provider.

How Envoy Builds B2B ERP Integrations

Envoy approaches B2B ERP integration as part of the core product, not as a secondary checkbox or add-on.

A Tailored Integration Based On ERP Type

For highly customizable ERPs like SAP, integrations often require unique file formats that transmit field-level data across major objects such as customers, products, orders, inventory, and invoices.

For more standardized ERPs like NetSuite, integrations are built via API. These are structured in a way that allows tailoring to brand-specific requirements while remaining maintainable across multiple brands using the same ERP.

This balance avoids two extremes:

• Generic connectors that miss important data
• Completely bespoke integrations that are impossible to support long term

Built For Apparel And Specialty Retail

Envoy B2B is intentionally built for brands in apparel, footwear, and their retailers.

That matters.

It means our integration logic reflects industry realities like size grids, order history visibility, and retailer-specific pricing structures. And since our integration is built as a core part of our platform, it isn’t designed to “kind of work” for every industry, it’s designed to specifically work very well for apparel and footwear brands, allowing them to offer a premium wholesale experience to their retailers.

That focus on industry specificity reduces guesswork in integration design, and makes the overall adoption process drastically easier.

Proactive Maintenance And Certification

When an integration is certified within an ERP ecosystem, the vendor is notified of platform updates in advance. This allows proactive updates before changes break functionality.

Middleware connectors are often built against a current ERP instance and then adjusted reactively when updates occur. That can introduce lag and unexpected costs.

Integration maintenance can’t be an afterthought, because if there is one constant, it’s that ERP systems are updated extensively and often. Updates break things, and downtime from lack of proactive maintenance can cost real business dollars.

Managed SaaS (mSaaS): Integration As A Long-Term Commitment

Enterprise B2B ERP integrations are rarely “set it and forget it.” ERP data fields evolve. Product models change. Brands expand internationally. Payment workflows shift. New operational requirements emerge over time.

Many integration models treat the initial build as a fire-and-forget project. Get the integration, and then it’s work complete. Once everything is live, additional requests are handled through change orders, add-on fees, or third-party consulting engagements.

Envoy B2B approaches integration differently through a managed SaaS (mSaaS) model. We don’t walk away once the integration is done.

What mSaaS Means In Practice

With mSaaS, the integration is built and maintained as part of the platform, for as long as a brand is using Envoy B2B. It is not a one-time deliverable.

Brands operate on a private instance of Envoy B2B, with a dedicated setup and software license. The integration is implemented quickly, similar to a traditional SaaS deployment, but it is not limited to a rigid, one-size-fits-all configuration.

More importantly, ongoing integration maintenance is built into the model.

That includes:

• Monitoring ERP updates
• Adjusting field mappings as business requirements evolve
• Improving sync logic over time
• Supporting enhancements without triggering repeated change orders

Integration development is treated as part of the product roadmap, not as an external bolt-on.

Predictable Cost vs Accumulating Change Orders

In traditional project-based integration models, the financial pattern often looks like this:

• Initial integration fee
• Additional fees for new fields or workflows
• Additional fees for ERP version changes
• Additional fees for deeper data sync requirements

Over several years, those incremental costs can exceed the original implementation budget.

With mSaaS, integration maintenance is a predictable subscription line item. There are no hosting fees layered on top and no surprise invoices tied to routine updates.

For enterprise brands operating at scale, that predictability matters as much as functionality.

Customization Without Owning The Burden

Building software in-house provides maximum control, but it also creates ongoing development responsibility. Your internal teams have to maintain integrations, manage ERP updates, and support evolving workflows.

Using a traditional off-the-shelf SaaS solutions means you can move faster, but it can limit customization and lock brands into a generic roadmap.

The mSaaS model is designed to bridge that gap.

Brands receive:

• A tailored implementation aligned with their wholesale model
• A defined roadmap of enhancements
• Dedicated support and development resources
• Automatic access to platform improvements over time
  

The result is not just an integration that works today, but one that adapts as the wholesale business evolves.

Real-World Example: When Roadmaps Don’t Bend

In one recent enterprise implementation, a global hockey equipment brand came to Envoy B2B after years on a competing platform. As their business expanded, their operational requirements became more complex. Retailers needed the ability to customize products with specific team logos, colorways, and branding elements directly within the wholesale ordering experience.

This was not a minor feature. Customization was directly tied to revenue.

However, because their previous vendor operated on a traditional SaaS roadmap model, these requests were repeatedly deprioritized. The integration and product roadmap had to serve a broad customer base, and brand-specific enhancements were pushed behind more generalized initiatives.

Over time, this limitation began to impact the brand competitively. Retailers increasingly expected customization capabilities, and without them, the brand risked losing orders to competitors who could support those workflows.

Under Envoy’s managed SaaS model, allocated development time is built into the subscription. That allowed the customization requirements to be implemented without restarting the contracting process or navigating repeated change orders. The integration and ordering logic were adapted to support logo and team-specific configurations in a way that aligned with the brand’s ERP and operational model.

This is a key distinction between the managed, vendor-built approach that Envoy B2B uses, and a middleware-driven or generic roadmap model. Middleware connectors and standardized SaaS platforms must be built for broad reuse across many companies. Deep, brand-specific logic often falls outside their standard configuration.

For enterprise wholesale brands, those “edge cases” are rarely edge cases at all. They are core to how the business competes.

Middleware vs Vendor-Built: Long-Term Tradeoffs

In case we haven’t made it clear, integration architecture will absolutely have a business impact.

Accountability

When middleware is involved, there are typically three parties: the ERP vendor, the e-commerce platform, and the middleware provider.

When something breaks, determining responsibility can take time.

With a vendor-built integration, accountability is centralized. That reduces ambiguity and accelerates resolution.

Implementation Timeline

Middleware can sometimes move faster initially by delivering a minimum viable connection.

However, minimally viable integrations often exclude deeper requirements such as order history sync, detailed product metadata, or advanced invoicing workflows.

Brands may go live quickly, but they’ll have to invest additional time down the line as they work to rebuild missing components.

Depth Of Data

Shallow integrations typically move customer and order data, and that’s it.

But a comprehensive integrations also handle:

• Order history
• Detailed product metadata
• Product images
• Invoices
• Payment reconciliation
• Clear bidirectional sync rules
  

Without that depth, manual processes creep back into operations, driving costs up.

This illustration demonstrates the key business objects synced in the Envoy B2B x NetSuite integration.

Error Handling And Visibility

How errors are handled is critical for ensuring smooth operations.

When middleware operates outside the ERP interface, error visibility can be less transparent. Brands may not discover sync failures until downstream issues occur, such as inaccurate inventory or missing orders. That’s going to create drag on your season, decreasing your ability to move product, lowering sales, increasing retailer frustration, and creating fire alarms for your reps.

In Envoy B2B’s NetSuite integration, errors surface within the NetSuite UI with clear messaging on why a sync failed and how to resolve it. This allows brands to spot the error before it becomes an issue, allowing you to resolve it quickly before it causes lost revenue.

Cost Over Time

Middleware solutions may appear less expensive upfront because they distribute development cost across many customers. However, customization requests, additional data mapping, and ongoing maintenance will increase the cost over time.

At Envoy B2B, we think the total cost of ownership should include not just initial implementation but years of operational adjustments.

When Middleware Might Make Sense

It’s not all doom and gloom though, because middleware is not inherently flawed, just limited. It’s something that can be good inside specific use cases, such as:

• Connecting standardized SaaS systems with predictable data structures
• Integrating non-core tools such as CRM to marketing automation
• Bridging short-term system gaps during transitions

In environments where integration requirements are relatively uniform and operational complexity is low, middleware can provide flexibility.

The question is not whether middleware works, but whether it aligns with the operational depth required for your wholesale B2B ERP integration.

Choosing The Right B2B e-Commerce ERP Integration Strategy

When evaluating your approach, consider:

• Does the integration reflect the realities of your industry?
• Who owns ongoing maintenance?
• How are ERP updates handled?
• How visible are sync errors?
• What happens when your business model evolves?

Integration architecture is not just a technical decision. It shapes operational efficiency, retailer experience, and long-term scalability.

Wondering what integration might look like for your brand, or have specific questions? Let us know, we're happy to chat.