An integration pays off as soon as your team retypes data from one system into another. An API integration moves orders, customers, stock or invoices automatically between your webshop, CRM, accounting software or marketplace, without manual work and without typos. What it costs and how long it takes depends less on the integration itself than on the system on the other side: how well it's documented, and how much data has to go back and forth. This article explains what an integration is, what drives the price, when an off-the-shelf tool is enough and how to start small.

The short version

  • An API is the official entrance to a system that other software can use to fetch or send data. An integration uses that entrance to let two systems talk to each other automatically.
  • The price depends mostly on the other system: its documentation, its test environment, and whether data flows one way or both ways.
  • Off-the-shelf tools like Zapier or Make are fine for simple, low-volume flows. With lots of data, custom logic or business-critical processes, a custom integration pays off.
  • An integration is never completely finished. APIs change, so plan for monitoring and maintenance from the start.

What is an API integration, in plain language?

Almost every modern software package has an API: an agreed way for other software to ask questions ("give me all new orders from today") or give instructions ("create this invoice"). Think of it as a service counter with fixed forms. An integration is the program that fills in those forms on your behalf, at the right moment and in the right format.

The result: an order in your webshop appears in your accounting software automatically, a new customer in your CRM automatically gets an account in your portal, and your stock is correct everywhere at once. Nobody has to copy and paste anymore.

Common integrations

  • Accounting: sending invoices and payments to your accounting software automatically.
  • CRM: customers, enquiries and touchpoints in one place, including those that come in through your website or app.
  • Payments: checkout via iDEAL, credit card or a provider such as Mollie or Stripe, including refunds and status updates.
  • Logistics: creating shipping labels and passing orders to a parcel service or fulfilment partner, with track-and-trace back to the customer.
  • Marketplaces: syncing products, stock and orders with platforms such as bol.com.
  • Stock and ERP: one source for stock and prices, so you don't sell what's no longer there.

What drives the cost and the timeline?

Two integrations that do the same thing on paper can differ a lot in effort. These are the factors that matter most:

  • The other system's documentation and test environment. An API with clear documentation and a test environment is quick to connect. Without a test environment, testing has to happen carefully with real data, and that takes time.
  • Login and access. Some systems grant access within a day; with others you have to apply as a partner or wait for the vendor.
  • Translating data. Every system names things differently. A "customer" in your webshop isn't the same as a "contact" in your accounting software. Pinning down that translation is often the most thinking work.
  • One way or both ways. Just sending data on is simpler than keeping two systems in sync when both can be edited.
  • Real-time or periodic. Updating every fifteen minutes is simpler than passing on every change instantly.
  • Volume and limits. Many APIs limit how many requests you can make per minute. With thousands of products or orders, the integration has to handle that smartly.
  • Error handling. What happens when the other system is briefly unavailable? A good integration retries and never loses an order.
  • Logging and alerts. You want to know something is wrong before a customer notices, not a week later.

Off-the-shelf tool or custom integration?

Ready-made options exist for many integrations: an app in the Shopify app store, a built-in connector in your accounting software, or a no-code tool such as Zapier or Make where you click flows together yourself.

Choose an off-the-shelf tool when

  • the flow is simple, such as adding a new form submission as a contact in your CRM;
  • only a little data moves per day;
  • a short outage doesn't cost revenue or customers;
  • a good connector already exists between exactly your two packages.

Choose a custom integration when

  • a lot of data flows through it, such as thousands of products or orders;
  • you need your own rules that an off-the-shelf tool can't handle;
  • the process is business-critical and you want to know exactly what happens when something fails;
  • the monthly cost of separate tools and tasks grows with your volume;
  • nothing exists for your combination of systems.

Often it's a combination: you keep your existing packages and only have the piece in between built. That hybrid approach is covered in Custom software or off-the-shelf: when does it pay off?.

How does an integration project run?

  1. Map the data. Which data goes from where to where, when, and what does each field mean on both sides?
  2. Agree what's leading. If stock differs between two systems, which one is right? That agreement prevents a lot of confusion later.
  3. Build. The integration itself, with error handling, retries and logging.
  4. Test with real data. Preferably in a test environment, then with a small number of real orders or customers.
  5. Go live. Often alongside the existing manual work first, so you can compare before letting the manual work go.
  6. Monitor. Alerts on errors and an overview of what has been passed on.

Tip: start with one flow, for example only orders from your webshop to your accounting software. Once that runs reliably, add the next one. You see results quickly and take little risk.

Maintenance: an integration is never completely finished

Vendors change their APIs: fields change, old versions are switched off, credentials expire. An integration that works perfectly today can suddenly stop a year from now. So agree up front who keeps an eye on the integration, who gets alerts when something fails and who updates it when the other system changes.

What does an integration cost?

An integration is often part of a larger project, such as a webshop, app or web application. With us, a project with integrations usually falls in the complete app or web application tier, roughly €10,000 to €15,000. How those amounts are built up is explained in How much does it cost to build an app?. A standalone integration with your existing systems gets its own fixed price after a free intake, depending on the factors above.

Weigh that against what the manual work costs you now. If someone retypes orders or updates stock every day, that often adds up to more than the integration itself within a year.

Examples from our projects

  • MyBeauty247: a Shopify webshop with thousands of products, linked to several marketplaces. A system syncs the orders, so all orders from the webshop and marketplaces sit in one central overview. Delivered within a tight deadline.
  • DenHaagTax: a custom booking system where bookings, dispatching rides and payments come together in one system. Since launch the company sees more bookings and lower operating costs.
  • Tapp: the POS tablet scans order QR codes and talks to the backend through integrations, and the touchscreens on the tap containers do the same. That way every part works with Tapp's existing systems.
  • Glasfixer: orders no longer have to be entered by hand, which saves 10 hours a week.

Want your systems connected?

We connect to the systems you already use, from CRM and accounting software to payment providers and parcel services, with a fixed price and deadline and maintenance after launch. Read more about custom web applications or webshops and e-commerce, or see how we work.