How a B2B Platform Connects to Any ERP via API (Without Replacing It)

You already run an ERP. It tracks every pallet in the warehouse, prints the invoices, and feeds your accountant. So the last thing you want is a B2B webshop that turns into a second source of truth nobody trusts. The good news is that a modern B2B platform does not replace your ERP. It talks to it over an API and lets the ERP stay the master. The hard part is knowing exactly what data moves, in which direction, how often, and which questions to ask before you sign anything.

What actually flows between the platform and your ERP

Picture a Tuesday morning at a distributor near Stuttgart. A customer logs into the portal, sees an item showing 240 units in stock, orders 60, and gets a confirmation. Behind that one click, three data streams did their job.

Stock levels and prices flow out of the ERP into the platform, so the shop shows what the ERP knows. Orders flow back from the platform into the ERP, so your warehouse and accounting see them without anyone retyping. Product data such as names, units, EAN or GTIN codes and customer assignments usually starts in the ERP too. Selldi connects to any ERP or accounting system over its API, so the ERP stays the single place where truth lives and the shop is just the window your customers look through.

The detail that saves arguments later is pricing. B2B is never one price list. You have per-customer rates, group discounts, and special deals for the buyer who takes a full truck every month. Those can come from the ERP or be managed on the platform, but they need to land in each customer's account correctly, every time, without a salesperson editing a spreadsheet.

Direction matters more than people expect

Most integration headaches come from getting the direction wrong. Two-way sync sounds reassuring, but you rarely want everything going both ways. Stock belongs in one direction, ERP to platform, because the warehouse is the only place that truly knows what is on the shelf. Orders go the other way, platform to ERP. Prices usually run ERP to platform, unless you want sales staff managing promotions in the shop.

Selldi syncs stock, prices and orders in both directions, so the systems stay in step. But the question to put to any vendor is the same: who is allowed to change this field, and where does that change start? If two systems can both edit the same number, you will eventually get a conflict, and conflicts in stock or price are exactly the kind your customers notice.

How often is often enough

There is a myth that B2B needs real-time, to-the-second inventory. For most wholesalers it does not, and chasing it only adds cost and fragility. What you actually need is a refresh frequent enough that a customer almost never orders something that just sold out.

Selldi syncs on a cycle of roughly every 15 to 60 minutes. For a distributor moving cement, fasteners or industrial supplies, where stock changes in batches rather than in milliseconds, that is plenty. A faster cycle only makes sense if you sell scarce, high-demand items where the last twenty units get fought over. Ask any vendor what the interval is, whether you can tune it per data type, and what happens to an order placed in the gap between two syncs. A good platform queues it and the ERP picks it up on the next pass instead of dropping it.

The questions to put to your vendor

Before you commit, get concrete answers rather than slides. A few separate a real integration from a demo:

• Which fields sync, in which direction, and on what schedule, written down, not waved away as full integration.
• What happens during an outage: if the ERP is down for an hour, does the shop keep taking orders and replay them, or does it block?
• How are per-customer and group prices mapped, so the right buyer sees the right number?
• How are product identifiers matched, SKU or EAN and GTIN, so the platform and ERP agree on what an item is?
• Who owns the integration when your ERP gets an update, you or them?

Ask how messy real life is handled, too. Plenty of B2B orders still arrive as a PDF, an email, or an Excel attachment from a long-standing customer who refuses to use the portal. Selldi uses AI to read those and push the order into the ERP automatically, so the integration also covers orders that never start as a clean click. Paired with a phone-based EAN and GTIN scanner that needs no app install, a salesperson on the floor can check stock and build an order against the same live data the API serves.

When this is not worth it

Honesty helps here. If you sell a handful of products to a dozen accounts and process a few orders a week, an API integration is overkill, and a shared spreadsheet with a phone call will outlast any software project. The same goes if your ERP is so heavily customized that nobody, including the people who built it, can describe its data model. The integration cost will balloon, and you should sort the ERP out first.

Integration also disappoints when the underlying data is dirty. If the same product exists three times under three SKUs, or your stock figures are already wrong in the ERP, syncing them faster just spreads the mess to your customers. Clean the data first, then connect.

Where it does pay off is the familiar case: a growing distributor selling across the EU, juggling several languages, currencies and per-market price lists, and drowning in retyped orders. Selldi handles multi-language and multi-currency export pricing and online payments by card or local methods, and a typical rollout runs about two weeks. You pay an implementation fee plus a subscription, with no commission on your sales, rather than handing over a cut of every order.

If you want to see how the data actually moves before committing anyone's time, the live demo is at demo.selldi.pl/showcase and questions go to helpdesk@selldi.pl. The point is not to replace the system that already runs your business. It is to give it a sales channel that keeps itself honest.