ERP Integration in B2B E-Commerce: SAP, DATEV, Dynamics

In B2B commerce, requirements differ fundamentally from B2C. Customer-specific pricing, complex discount structures, multi-level approval processes and recurring orders require a seamless data flow between online store and ERP system. Without this connection, information silos emerge that lead to delivery delays, incorrect pricing and unnecessary inquiries.

According to a Gartner study (2025), 78% of successful B2B merchants (Gartner, 2025) already rely on automated ERP connections for their online stores. The reason: companies with integrated systems report 40% faster order processing and a significant reduction in error rates during document capture (Forrester, 2024). For mid-market companies using Shopware as their B2B platform, ERP integration is a decisive competitive factor.

Before an ERP integration is technically implemented, the question of data authority must be clarified. Master Data Management (MDM) defines which system is the leading source for which data entity. In practice, the ERP system is the leading source for customer master data, price lists and item numbers in most B2B scenarios, while the online store retains authority for shopping carts, ordering processes and product presentations.

The greatest challenge in master data management is harmonizing different data models. An item in SAP Business One has a different structure than a product in Shopware -- different fields, data types and hierarchies must be cleanly mapped to each other. A concrete example: SAP uses units of measure such as "Pcs" (pieces), "Ctn" (cartons) or "Plt" (pallets), which need to be translated into understandable ordering units in the store. According to a study by Fraunhofer IML, 32% of all ERP integration projects fail due to insufficient master data management (Fraunhofer IML, 2024). A structured mapping table created before project start and approved by both business departments significantly reduces this risk.

SAP Business One is the most widely used ERP system in the German mid-market, with over 80,000 customers worldwide (SAP, 2025). Integration with a B2B store requires a deep understanding of SAP data structures -- particularly business partner hierarchies, price lists and document types. Via the SAP Service Layer API (OData-based), all relevant business objects can be synchronized bidirectionally.

Typical integration points include item master data with price lists and inventory quantities, business partners with delivery addresses and payment terms, as well as orders, invoices and credit notes. For Shopware-based B2B portals, a middleware architecture has proven effective, acting as a mediation layer between the store API and SAP Service Layer. This middleware handles data validation, transformation and error handling.

Approximately 2.7 million companies in Germany use DATEV for their financial accounting (DATEV, 2025). Integrating a B2B store with DATEV automates the entire document flow from order through invoice creation to posting. Manual CSV exports and re-imports are eliminated, and accounting always works with current data.

The DATEV interface is based on standardized formats such as the DATEV posting batch for journal entries and the DATEV XML format for online document exchange. Modern integration solutions additionally use the DATEV API for real-time synchronization of invoices and payment receipt notifications. Particularly relevant for B2B merchants is the automatic assignment of debtor numbers and the correct posting of different tax rates.

Automating the DATEV document flow typically saves trading companies 8--12 hours per week (project experience) in accounting effort. Furthermore, machine processing reduces the risk of erroneous postings that could lead to objections during tax audits.

Microsoft Dynamics 365 combines ERP and CRM functionality on a single platform, making it particularly attractive for B2B companies wanting to map customer relationships and merchandise management in one system. Around 500,000 companies worldwide rely on Dynamics 365 (Microsoft, 2025). Integration with a B2B online store enables a 360-degree view of customer interactions -- from the first inquiry in the store to recurring orders.

The connection is established via the OData-based Dynamics API, which provides standardized access to all entities. For Shopware-based B2B stores, an event-driven integration model has proven effective: the store sends webhooks to the middleware for relevant events (order, customer registration, price inquiry), which transforms the data and forwards it to Dynamics. Conversely, Dynamics pushes changes to item master data or inventory quantities to the store via change tracking mechanisms.

Particularly valuable in the B2B context is the ability to leverage CRM data from Dynamics in the store. Field sales representatives see the same prices and availability in the CRM as the customer sees in the self-service portal. Quotes created in the CRM can be stored directly as order templates in the store. This consistency measurably increases sales efficiency.

The order-to-cash (O2C) process encompasses the entire journey of an order from placement in the store through order creation in the ERP, picking, shipping, invoicing, and finally payment receipt. In many B2B companies, this process is still partially manual -- resulting in longer throughput times than necessary and errors at handover points.

A fully integrated O2C pipeline eliminates these manual handover points. As soon as a customer places an order in the B2B portal, the order is automatically created in the ERP -- including all line items, customer-specific prices, delivery addresses and payment terms. The ERP triggers picking, generates the delivery note and creates the invoice. Shipping status is synchronized back to the store via the middleware, so the customer can check their order status at any time in the self-service portal. According to a McKinsey study (2024), complete O2C automation reduces the throughput time from order to payment receipt by an average of 30 to 50 percent (McKinsey, 2024).

For B2B merchants, the availability display in the store is a critical factor. Business customers expect reliable information about whether and when an item is deliverable -- particularly for large orders that influence production planning. Real-time inventory synchronization between ERP and online store ensures that availability, minimum order quantities and expected delivery dates are always current.

Technical implementation typically uses a delta sync mechanism: instead of periodically reconciling the entire inventory, only changes are transferred. SAP Business One provides change logs via the Service Layer API that return all inventory changes since the last retrieval. For a typical B2B catalog with 20,000 to 50,000 items, this approach reduces the transfer volume by over 90 percent compared to a full reconciliation (project experience). For time-critical items -- such as spare parts in manufacturing -- an additional event-based push can be set up that immediately updates inventory in the store with every booking.

B2B companies frequently operate multiple warehouse locations or work with dropshipping partners. Inventory synchronization must in this case map location-specific availability. The ERP maintains inventory per warehouse; the store must present this information so that the customer sees total availability and can optionally select a preferred delivery source. If an item is unavailable at location A, the middleware can automatically redirect to location B and communicate this transparently in the store.

Dropshipping integrations add another layer of complexity: inventory does not reside in your own warehouse but with the supplier. The integration solution must query the dropshipping partner's availability in real time and forward orders directly to their system. The challenge lies in consolidating the document chain -- delivery notes and invoices must be mapped as a unified transaction in the ERP despite separate logistics.

Choosing the right integration architecture determines the maintainability, scalability and future-proofing of the entire solution. In practice, three approaches have been established: point-to-point connections, middleware-based integration and API hub solutions. For B2B scenarios with multiple systems to integrate, we generally recommend a middleware approach that serves as a central hub.

A central aspect of middleware architecture is data transformation. ERP systems and e-commerce platforms use different data models -- an item number in SAP is not identical to the product number in Shopware. The middleware handles the mapping between these data models and ensures that information is transferred consistently and completely. Furthermore, the middleware layer enables a clean separation of systems: store updates or ERP upgrades can be performed independently, as long as API contracts are maintained.

An ERP integration project in a B2B environment typically follows a structured process that can be divided into five phases. The total duration depends heavily on the complexity of the existing IT landscape and the scope of processes to be integrated. For mid-market companies, project timelines of 8 to 16 weeks for an initial integration are realistic.

ERP integration projects are demanding and carry specific risks. The most common challenges include inconsistent master data, historically grown data structures in the ERP and missing API documentation for older system versions. An upstream data cleansing effort is often the key to project success.

Another frequent issue is performance with large data volumes. B2B catalogs with 50,000 or more items and hundreds of customer-specific price lists require well-thought-out synchronization strategies. Instead of a complete data reconciliation, a delta sync approach has proven effective: only changed records are transferred, identified via timestamps or change tracking mechanisms of the ERP system.

Multi-tenancy is particularly relevant for groups and corporate entities. When multiple companies operate on a single Shopware instance, the middleware must assign the correct ERP tenants and cleanly separate data. This affects item master data as well as customer data and document chains.

Many B2B companies still operate older ERP connections based on file exports (CSV, EDIFACT) or direct database access. These legacy integrations are error-prone, difficult to monitor and do not scale with growing order volumes. Migration to a modern, API-based integration architecture is a common reason for engaging a specialized agency.

The most proven migration strategy is the strangler fig pattern approach: instead of replacing the old integration in one go, the new middleware is built in parallel. Data flow by data flow is migrated from the old to the new solution -- first non-critical data such as item master data, then inventory synchronization, and finally the transaction-critical ordering processes. During the transition phase, both systems run in parallel and results are compared. This approach minimizes risk and allows a fallback to the old solution at any time if problems arise.

Special attention must be paid to migrating historical data. Customer histories, open items and ongoing orders must be transferred to the new system without disrupting ongoing operations. A structured consultation helps determine the right migration sequence and plan test phases realistically.

The ERP integration landscape is constantly evolving. Trend technologies such as Event-Driven Architecture, GraphQL APIs and API-first approaches open new possibilities for flexible and performant integrations. SAP is increasingly focusing on cloud-native integration with the SAP Business Technology Platform (BTP), while Microsoft provides a unified data platform for Dynamics 365 with Dataverse.

For B2B merchants, this means concretely: investing today in a modern, API-based integration architecture positions you well for future requirements. Connecting additional systems -- such as a PIM system for product data management or a WMS for warehouse logistics -- is significantly easier with existing middleware infrastructure than with point-to-point architecture. The investment in a solid integration architecture pays off in the long term through lower expansion costs and higher reliability.

The topic of AI-supported data processing is also gaining importance: intelligent matching algorithms can automate item mapping between systems, detect anomalies in synchronization data and continuously improve data quality. Combined with professional monitoring, the integration solution can be proactively monitored and optimized.