Integrating an ERP with an e-shop means products and prices flow from the ERP to the store, stock updates in both directions, and every order lands in the ERP without retyping — issuing its tax document on its own.
The gain is not only time. It is that you stop selling products the warehouse does not have.
Still keying in orders by hand?
Request a free technical review and you will get a cost and time estimate for your specific setup.
What exactly syncs
A proper integration is not “one connection”. It is five flows with different directions and frequencies.
| Flow | Direction | Typical frequency |
|---|---|---|
| Products, codes, descriptions | ERP → e-shop | Every 1–6 hours |
| Prices and price lists | ERP → e-shop | Every 1–6 hours |
| Stock | ERP → e-shop | Every 5–15 minutes, or real time |
| Orders | e-shop → ERP | Real time |
| Order status & courier label | ERP → e-shop | On every change |
The stock line is what determines the quality of the build. Syncing every six hours means that on a promotion day you will sell things you do not have.
The three implementation routes
| Route | How it works | Suits | Risk |
|---|---|---|---|
| Direct API | The e-shop talks straight to the ERP | Stable, standard flows | A change on either side breaks the other |
| Middleware / connector | A layer in between translates both | Complex flows, several channels | Extra cost and another thing to maintain |
| Scheduled files (XML/CSV) | Files exchanged at set intervals | Small volume, simple catalogue | Latency; unsuitable for live stock |
The practical rule: if you sell only through your own e-shop and your catalogue is standard, a direct API is enough. If you also sell on marketplaces or in a physical shop, middleware proves cheaper within the first year.
The six things that break
These separate an integration that works from one that causes trouble every Monday.
- Code matching. The ERP code and the e-shop code must map one to one. Missing mappings lose orders.
- Product variants. Size and colour are separate codes in the ERP and one page in the e-shop. This is the most common failure point.
- Concurrent orders. Two customers buy the last unit. You need stock reservation, not simple updating.
- Returns and cancellations. The credit note and the stock return must flow back to the e-shop.
- VAT rates. Different rates per category, plus shipping and discounts. An error here means wrong tax documents.
- Unpaid orders. An order that was never paid should neither reserve stock nor issue a document.
Ask your implementer to show you how each of the six is handled, with a real example. The answer separates the serious from the rest.
What does it cost and how long does it take?
| Scenario | Cost | Duration |
|---|---|---|
| Basic B2C sync (products, prices, stock, orders) | €1,200 – €3,500 | 1–3 weeks |
| Advanced B2C (multiple warehouses, variants, statuses) | €3,500 – €7,500 | 3–6 weeks |
| B2B (per-customer pricing, credit limits, approvals) | €6,000 – €15,000+ | 6–12+ weeks |
The costs that never appear in the initial quote:
- ERP data cleanup: €300 – €2,000. Duplicate codes and inconsistent units must be resolved first.
- Staging environment: essential for any serious shop, so you are not testing on live orders.
- Courier and marketplace connections: €500 – €3,000.
- Monthly monitoring and maintenance: €50 – €250.
That last line is not optional. An unmonitored integration will stop at some point, and you will hear about it from a customer.
Holding an integration quote and unsure what is missing?
Send it to us and we will tell you which of the six critical cases it covers.
Invoicing: the part that is now mandatory
From 1 October 2026, electronic invoicing becomes mandatory for all Greek businesses. The ERP–e-shop integration must end in automatic issuing and transmission of the tax document.
The chain you want is: order in the e-shop → record in the ERP → document issued → transmitted to the tax authority → emailed to the customer.
If any link is manual, the chain will break during a peak. The steps and costs are set out in our guide to connecting an e-shop to myDATA.
What to demand in writing in the quote
- Which flows are covered and at what frequency each one runs.
- How the six critical cases above are handled.
- What happens on failure: retries, queueing, and who gets alerted.
- A staging environment and the scenarios that will be tested before launch.
- Who owns the integration code, and what happens if you change partner.
- Maintenance cost per month and what it covers.
The third point is the one that gets forgotten and costs the most. An integration with no retry mechanism loses orders silently.
How to check it is working
Set up three simple checks from day one.
| Check | Frequency | What failure means |
|---|---|---|
| E-shop orders versus ERP orders | Daily | Orders are being lost in transit |
| Documents without a registration number | Daily | A problem transmitting to the tax authority |
| Stock differences between e-shop and ERP | Weekly | The sync is lagging or broken |
Two weeks of daily checking after launch catches almost every problem. After that, a weekly glance is enough.
Frequently asked questions
Do I need an ERP to start an e-shop?
No. Start with the e-shop and add an ERP when your warehouse or order volume demands it. The context is in our guide to what an ERP is.
Does it work with WooCommerce and Shopify?
With both. WooCommerce gives more freedom; Shopify sets tighter limits on what can be changed.
How often should stock update?
For a shop running promotions with limited units, every 5–15 minutes or in real time. For a catalogue with deep stock, hourly is fine.
What happens if the ERP goes down?
Orders should queue and pass through once it returns. Ask for this explicitly.
Can I do it with an off-the-shelf plugin?
For simple cases, yes. For variants, multiple warehouses, or B2B pricing, almost never without customisation.
The first step before requesting quotes
Write down three numbers: how many products and variants you have, how many orders a day you take at peak, and how many channels you sell through.
With those, any serious implementer can tell you whether you need a direct connection or middleware — and quote a real price instead of a range.
For the wider cost of the store, see our guide to e-shop costs, and for its visibility, e-shop SEO.
Next step
Book a free 30-minute meeting with the team at The Dev Alley. We will look at your ERP and e-shop together and tell you which architecture costs less over time.