Connector or custom integration?

A ready-made connector or plugin is enough if your process follows the standard, the fields you need are covered and the volume fits the license. A custom integration pays off if special cases such as credit notes, partial deliveries or variants matter, if a system has no API, or if you want to own the code yourself.

For almost every common combination of shop, ERP, CRM and accounting there are ready-made apps and plugins. That is a good thing. This page helps you check honestly whether a ready-made connector covers your case before you spend money on custom development.

What is the difference?

A connector or plugin is a finished product from a vendor or third-party provider. It connects two specific systems under fixed rules and is adjusted through settings. You pay a license or a monthly fee.

A custom integration is programmed for your process. It maps exactly your data objects, rules and special cases. You pay for development and operation. With myInterface, you own the code.

In between are iPaaS tools such as Zapier or Make, where you click your own workflows together. You will find the comparison in the guide Zapier alternative.

When is a ready-made connector enough?

• Standard process

  Orders and invoices run without exceptions. No partial deliveries, no ad hoc credit notes, one currency, one sales channel.

• Fields are covered

  The connector already transfers every field you need in the target system. You do not have to enter values by hand afterwards.

• Vendor maintains it actively

  The connector gets regular updates and supports the current versions of both systems.

• Costs fit

  The license stays affordable as volume grows, and you do not need expensive add-on modules.

If all four points apply, take the connector. It is set up faster and almost always cheaper than custom development.

When is a custom integration better?

• Special cases are routine

  Credit notes, partial deliveries, tiered discounts, variants, multiple warehouses or differing tax rates. This is where many connectors stop.

• A system has no API

  Legacy systems, industry software or databases without an interface are hard to connect with ready-made products. More under Integration without an API.

• More than two systems

  Shop, ERP and accounting are supposed to work together. With three connectors you get three rule sets that can contradict each other.

• Control and ownership

  You do not want to depend on a plugin's pricing policy or its continued existence. See vendor lock-in.

Criteria compared

Checklist: how to evaluate a connector before you buy

• Write down your five most frequent processes, including the awkward cases. Run each one through during the trial period.
• Check field by field what arrives in the target system. Is a field missing that your tax advisor or the warehouse needs?
• What happens with cancellations, credit notes and partial deliveries?
• How does the connector report errors? Can you see which record was not transferred?
• When was the last update? Are the current versions of both systems supported?
• Read reviews specifically for reports of wrong amounts, accounts or duplicate records.
• Project the license cost for the volume in three years, not today's volume.
• Find out where the vendor processes the data and whether it offers a data processing agreement (AVV).
• Ask what happens to your data and settings if you cancel or the product is discontinued.

Where ready-made connectors typically hit their limits

The limits rarely show up with the first data object. Orders almost always arrive. It gets difficult with information that changes after the order or that only matters in your company:

• Status changes: Payment status, shipping status or cancellations should flow back to the originating system. Many connectors transfer in one direction only.
• Variants and sets: Items with sizes, colors or bills of materials are modeled differently in the shop than in the ERP.
• Posting logic: Payment provider fees, vouchers, shipping costs with their own tax rate or deliveries abroad require separate accounts and tax keys.
• Custom fields: Cost centers, project numbers or free-text fields that your team uses are often not provided for in the standard product.
• Multiple channels: Shop, marketplace and point of sale should all feed the same accounting, each with its own rules.

Test these points with real sample data. A demo with three clean test orders rarely shows what happens at month-end close.

What to prepare for the decision

You do not need a technical specification to decide well. Three things are enough: the list of systems involved with version and plan, a description of the processes that run by hand today, and a few real examples, including the difficult ones. With that, the free 30-minute integration check can clarify whether an existing connector is enough or which part should be built custom.

How you know the connector is no longer enough

Typical signs are recurring manual work after every transfer, correction postings at the tax advisor, spreadsheets in which someone tracks discrepancies, and workarounds that only one person understands. If you spend time on rework every week, it is worth looking at the total cost. You will find the mental model for that under What does an integration cost?

Updated: 10/20/2026