What is an ERP system?
An ERP system is the business's hub where finance, inventory, purchasing, and orders come together in one shared data model. CRM and e-commerce usually sit outside it, connected separately. Swedish examples include Fortnox, Visma, Business Central, and SAP. Integrating with an ERP is often the hardest part of a project, since the system is central and sensitive.
ERP systems, or business systems, are the backbone of administration for most businesses of any size. Yet it’s not always clear what an ERP actually is, where its boundaries lie, and why it so often becomes the trickiest part to connect with other systems. Here’s the explanation for anyone commissioning development work.
The definition
ERP stands for Enterprise Resource Planning, sometimes called the business system. It’s the central system where a company’s core processes come together – above all finance, inventory, purchasing, and orders – in one shared data model. The point is precisely that sharing: instead of every department having its own isolated solution, the information meets in one place.
That makes the ERP the business’s hub. When an order is placed, an item is picked from inventory, and an invoice is created, it all ties together in the same database, against the same numbers. Everyone sees the same reality, and data doesn’t need to be entered in multiple places. That coordination is the whole idea of a business system, and the reason it often ends up being the single most business-critical system of all.
What’s included – and what isn’t
A common source of confusion is where the ERP’s boundaries lie. The core is clear: finance, inventory, purchasing, and order management, and for many businesses also production and HR administration. These are the internal resource flows the business system holds together.
What’s often not included is at least as important to know. CRM – the system for customer relationships and sales – usually sits outside it, as does e-commerce. These are typically run in their own specialized systems that connect to the ERP rather than being part of it. Exactly where the line is drawn differs between products and setups, but the rule of thumb holds: ERP handles the internal flows, while customer-facing systems tend to stand alongside it and integrate. Understanding that split saves a lot of confusion in a project.
Swedish examples
To make it concrete, there’s no shortage of business systems on the Swedish market, suited to different sizes and needs. Among small and mid-sized companies, Fortnox and Visma are common choices. Microsoft Dynamics 365 Business Central is widespread among mid-sized businesses, and SAP often shows up at larger companies with complex flows.
Which one fits depends entirely on the business’s size, industry, and requirements – there’s no business system that’s right for everyone. What matters for a development project isn’t which name is on the ERP, but knowing which one it is and how it can be integrated with.
A concrete scenario
Picture a trading company that wants to build a customer portal where customers can see their own orders, stock levels, and invoices. The portal itself is straightforward to build. The challenge lies in it having to pull all that information in real time from the company’s ERP – that’s where orders, inventory, and finance actually live.
Suddenly the project is less about the portal and more about the connection to the business system: how it reads data securely, how often it updates, and what happens if the ERP responds slowly. That integration becomes the heaviest part of the project, while the portal itself is the easier piece. It’s a pattern that recurs in almost every project that touches an ERP.
Why ERP integrations are difficult
That scenario points to a truth worth taking seriously: integrations with an ERP are often the hardest part of an entire development project, for several reasons.
First, the business system is central and sensitive – it carries the business’s most critical data, so an error in the connection can have serious consequences. Second, many business systems, especially older ones, are built in a way that makes them awkward to connect to. And third, precisely that critical nature demands extensive testing before anything goes live.
For you as the buyer, the lesson is to find out early how your ERP can be integrated, and to involve someone who knows the system already in the planning. Expect the connection, not the new system itself, to be the heaviest item. At Weapp we’ve built integrations with business systems in many projects, and that experience is often what determines whether such a project stays on time and on budget. If you’d like to talk through an integration you’re facing, get in touch.
Frequently asked questions
What is an ERP system, in simple terms?
ERP stands for Enterprise Resource Planning, sometimes called the business system. It's the central system where a company's core processes come together – finance, inventory, purchasing, and orders – in one shared database, so everyone works from the same information. Instead of separate islands for each department, the ERP becomes the hub where the numbers meet and stay aligned. It's often the backbone of a business's entire administration.
What's typically included in an ERP system, and what isn't?
The core is finance, inventory, purchasing, and order management, sometimes production and HR too. What's often left outside is CRM – customer relationships and sales – and e-commerce, which are usually run in their own systems that connect to the ERP. Exactly where the line falls differs between products, but the rule of thumb is that ERP handles the internal resource flows, while customer-facing systems tend to stand alongside it.
Which ERP systems are common in Sweden?
There are several, suited to different sizes and needs. Among small and mid-sized companies, Fortnox and Visma are common. Microsoft Dynamics 365 Business Central is used by many mid-sized businesses, and SAP is common among larger companies with complex flows. Which one fits depends on the business's size and requirements – there's no single right answer for everyone, and switching between them is rarely trivial.
Why are ERP integrations so difficult?
Because the ERP is central, sensitive, and often complex. It holds the business's most critical data, so an error in an integration can have serious consequences. Older business systems also sometimes have limited or awkward ways of connecting to them. Getting a new solution to talk to the ERP correctly and securely is therefore often the most time-consuming and risky part of an entire development project.
We're building a system that needs to talk to our ERP – what should we think about?
Find out early how your ERP can be integrated and what it allows, since that affects time and cost more than almost anything else. Involve someone who knows the business system already in the planning stage. Don't underestimate testing: since the ERP carries critical data, the connection must be tested thoroughly before it goes live. Expect the integration, not the new system itself, to be the heaviest part of the project.