ERP system: what it is and how it connects to your online store

In short: an ERP system (Enterprise Resource Planning) is software where a company keeps its inventory, purchasing, sales, invoicing and accounting in one database. An online store uses four of its modules: inventory, prices, sales and customers. The ERP is the source of truth for stock and prices, the store sends orders back, and products are matched by SKU or barcode.

This guide is for merchants across Europe who run a warehouse, a physical shop or a large supplier catalog and want the website to show the right stock without anyone retyping numbers. It also shows how the connection works in CloudCart, the ecommerce platform where ERP, inventory and POS systems connect as apps or through the API.

What is an ERP system, in simple terms?

An ERP system is a program in which every department writes its data into one shared database, so the warehouse, sales and accounting work with the same numbers. When the warehouse books in a delivery, the new stock is visible to sales at once. When the till sells an item, the quantity goes down for everyone.

The term ERP was coined by the research firm Gartner in 1990 as an extension of MRP (Material Requirements Planning, the planning of materials in manufacturing), according to Wikipedia. ERP is the most common business software in Europe: in 2025, 41% of small EU enterprises (10 to 49 employees) and 89% of large ones (250 or more) used an ERP application, according to Eurostat.

An example: a cosmetics brand with a shop in Vienna and an online store shipping to Austria and Germany. With an ERP, a delivery of 200 face creams is booked in once, a sale at the till reduces it, and the online order lands in the same program for invoicing. Nobody corrects the website stock by hand each morning.

Which ERP modules matter for an online store?

An ERP system is built from modules, and an online store usually works with four of them: inventory, prices, sales and customers.

Module	What it manages	What the online store gets or gives
Inventory and stock	Quantities per warehouse and location, deliveries, stock counts	The stock level the customer sees on the site
Prices and price lists	Retail and wholesale prices, promotions	The product price, sometimes a price per customer group (B2B)
Sales and orders	Orders from every channel	The online order is sent into the program
Customers (CRM)	Contacts and purchase history	A new customer from the site is created in the program
Finance and accounting	Invoices, credit notes, payments, VAT	The invoice and credit note for the online order

If you sell to consumers in other EU countries, the finance module also has to apply the right VAT rate per destination once you pass the €10,000 threshold for intra-EU distance sales. The rules and filing steps are in the guide to OSS VAT for cross-border EU sales.

How does an ERP system help an online store?

An ERP system helps an online store by removing manual retyping between the warehouse, the website and accounting: every number is entered once and reaches every channel.

In practice: a delivery is booked in once and reaches the site at the next sync, a sale in the shop lowers the online stock too, a new price goes to the site and the product feeds from one place, and the online order arrives in the program for the invoice without retyping.

ERP or inventory software: what is the difference?

Inventory software tracks goods, sales and usually invoices, while an ERP system covers the whole company, including finance, purchasing and production. For most online stores, inventory software is enough, and the connection to the site works the same way for both: stock and prices flow into the store, orders flow out.

Criterion	Inventory software	ERP system	POS (till system)
What it manages	Goods, deliveries, sales, invoices	Every business process in one database	In-store sales and the shop's stock
Who it suits	Shops and small to mid-sized companies	Companies with several departments, production or a chain of stores	Shops and restaurants
Connection to the online store	The same: products are matched by barcode or SKU, stock and prices come into the site, orders go into the program

Cloud ERP or on-premise ERP?

A cloud ERP runs on the vendor's servers and opens in a browser, while an on-premise ERP runs on a server or computer in your company. For the online store the difference is availability: a cloud program can exchange data with the store at any time, an on-premise one only while the company server is on, online and protected.

GDPR matters here too, because the ERP holds names, addresses and order histories of your online customers. A cloud vendor that stores this data on your behalf is a processor, and Article 28 of the General Data Protection Regulation requires a written contract with it. Sign the vendor's data processing agreement before the first sync. The wider privacy checklist is in the guide to GDPR and cookies for an online store.

An on-premise program does not have to be replaced for the website: the connection works with both types, as long as the server is online and secured.

How to choose an ERP system for an online store

Choose an ERP system for an online store by four things: whether it connects to your store platform, which data it exchanges and in which direction, how often it updates stock, and what it costs including rollout.

1. Check how it connects. A ready-made connection installs as an app and needs no developer. Any other system connects through the store's API. The list of ready-made connections in CloudCart is on the page online store connected to inventory software, ERP and POS.
2. Look at the direction of the data. Some connections only bring products and stock in and send no orders back, so invoices for online orders stay manual work.
3. Compare the update pace. Connections update stock anywhere from every few minutes to once a day. The more you sell in a shop or on other channels, the faster the sync you need.
4. Check the languages, currencies and countries. If you run a separate store per country, each with its own language and currency, the ERP has to keep prices per market and apply the VAT of each destination country.
5. Plan for e-invoicing. Under the EU package VAT in the Digital Age, in force since 14 April 2025, digital reporting and e-invoicing for cross-border B2B sales inside the EU apply from 1 July 2030 (European Commission). An ERP that can already issue structured e-invoices saves a second project later.
6. Count the full cost and ask about returns. Include rollout, training, support and extra users, and how returned goods reach stock, since EU consumers can withdraw from an online purchase within 14 days. See returns and consumer rights.

How do you connect an ERP system to an online store?

An ERP system connects to an online store in three ways: a ready-made app, a direct API integration, or a supplier catalog imported as a file. The program decides which one applies. In every case each product needs the same code (SKU or barcode) in both systems, otherwise the sync cannot tell which record belongs to which.

A ready-made app, such as the one for Finale Inventory, a cloud warehouse management system, installs from the admin. An API integration is built by your developer or ERP vendor. A supplier catalog arrives as an XML or CSV file with prices and stock, refreshed on a schedule. See product import from CSV and XML.

In CloudCart each ready-made connection is an app in the admin, under Apps with the name of the program.

1. Clean up the codes. Every product and variant needs a SKU or barcode that is identical in the store and in the program. A product without a matching code is imported as a new one, which is how duplicates appear. See barcodes, EAN and GS1 for products.
2. Decide which system leads on what. The usual split: the program leads on stock and price, the store leads on orders, customers, descriptions and photos.
3. Install the connection. In the admin open Apps, choose the program and enter the access details. For Finale Inventory these are the account name, a username and a password.
4. Choose the mode, warehouse and matching field. Finale Inventory, for example, either imports products and updates quantities or only updates quantities, takes stock from the facility you pick, and matches its Product ID, UPC or EAN to the SKU in CloudCart.
5. Run the first sync. In the import history, check how many products were created, how many updated and whether there are errors.
6. Place a test order. Order from the site and check that the order reached the program. The order history in CloudCart shows whether the send succeeded or failed, with the error message.

Is the ERP sync two-way?

The sync between an ERP and an online store is usually two-way, but each kind of data travels in one direction only. Stock and prices come from the program into the store. Orders and customers go from the store into the program. Supplier catalogs are the exception: products only come in, and no orders go back.

Conflicts are settled by which system leads: if the program leads on price, a price changed by hand in the admin is overwritten at the next sync. Keep descriptions and SEO texts under the store's control.

Returned goods also reach the stock figure. A return marked as received in the admin puts the quantities back in stock and issues a credit note.

How fast does the ERP update stock on the site?

Stock from an ERP updates in the store at the pace of the program itself, from every few minutes to once a day. A faster sync means fewer orders for items that have already sold in the shop or on another channel.

Ready-made connection	Type	Into the store	Out of the store	Update pace
Finale Inventory	Cloud warehouse management	Products, quantities	Orders, customers	Product data every 8 hours, orders when placed
Micro.bg	Cloud accounting and inventory	Stock, prices	Orders, right away	Every 3 minutes
PosMaster	POS and warehouse	Catalog, stock	Orders at a chosen status	Catalog once a day

The risk of a slow sync is concrete. If the catalog updates once a day, the last unit sold at the till at 10 a.m. stays visible online until the next cycle. Product feeds such as Google Shopping carry the same outdated figure. How feeds take stock is in the guide to Google Merchant Center and Google Shopping.

If your program syncs rarely, keep a separate buffer of fast sellers for the website, switch off selling at zero stock for items you cannot deliver later, and run a manual sync before campaigns such as Black Friday.

My ERP is not on the list. What now?

If your ERP or inventory software has no ready-made app, it connects through the store's API. Your developer or your software vendor builds it, or the CloudCart team builds it as a project with you.

• REST API. The program reads and updates products, stock, prices, customers and orders. API keys are created in Settings → Api keys. The REST API is included from the Starter Pack plan up, with a limit of 50 requests per minute on Starter Pack, 100 on CC Pro and 150 on CC Master (see /pricing).
• Webhooks. The store notifies the program about 20 event types, such as a new order, with the store's API key in the X-CloudCart-ApiKey header. Set them in Settings → Webhooks.
• PAT tokens. Keys with their own permissions, expiry and allowed IP addresses, for the CloudCart CLI and the GraphQL Admin API. Documentation is on the developers page.

Before you commission a connection, check how many products lack a SKU or have different codes in the two systems. Questions about the API go to support@cloudcart.com.

ERP and an AI assistant: reports and checks in one sentence

An AI assistant connected to the online store reads products, stock and orders and answers in plain language,. In CloudCart the connection uses a PAT token: Claude Code, ChatGPT/Codex, Gemini CLI, Cursor or VS Code get exactly the permissions you grant.

Typical requests: "Show me the products without a SKU or barcode" before the first sync, "Which products are below 5 units? Make me a reorder table", or "Here is a stock export from the ERP. Which products have a different quantity or price in the store?" The assistant compares by SKU and returns only the differences.

1. Create a token. The store owner opens Settings → PAT tokens. Read Only is enough for reports; for changes, choose permissions per area such as products or inventory.
2. Restrict the token. Set an expiry date and, if you want, up to 20 allowed IP addresses.
3. Confirm every change. Store changes have no undo button.

How to connect Claude Code to your store and what to write to it is explained step by step in Claude Code: how to run your online store with Claude. The same works with ChatGPT and Codex.

Common mistakes when connecting an ERP to an online store

Most problems with an ERP connection come from the data: codes, prices and fields. These are the most common mistakes and how to avoid them.

1. Products without a code or with different codes. If the SKU or barcode does not match, the sync creates a new product. Reconcile the codes before the first sync.
2. Prices changed in two places. Once the program leads on price, run promotions in the program or as a discount in the store, otherwise the next sync wipes them.
3. One price for every country. If you run a separate store per market, map each store to its own price list and currency in the ERP.
4. Going live without a test order. Place at least one order from the site and check it in the program before you launch a campaign.

When does an online store need an ERP system?

An online store needs an ERP system or inventory software when the same goods are sold in more than one place and stock is copied by hand. If you only sell online and manage the warehouse yourself, the stock in the store is enough: by default the store keeps a single stock count per item.

Typical signs: a physical shop or warehouse selling the same goods online, marketplaces or several country stores sharing one stock, and someone reconciling spreadsheets while customers order items that are out of stock.

If you run several stores, for example one per country with its own language and currency, shared inventory updates across them, and the ERP updates them all. How to set up the stores is in multilingual, multicurrency and multiple stores. If customers need to see stock at a specific warehouse, for example stock in Munich for a customer near Munich, the Store Locations app keeps a separate stock figure per location and shows it to customers in the linked geo zone. The details are on the warehousing, fulfillment and ERP page. For larger businesses that need a PIM, a B2B portal, an ERP hub or several stores, see Enterprise.

On every plan, sales in CloudCart carry a 0% commission. New to this? Start with how to create an online store. Create a store for €1 and connect your program from Apps in the admin.

Frequently asked questions