Having an interface built: what an API integration costs and what it depends on
Shop and inventory, CRM and accounting, website and ticket system: almost every company has systems that don't talk to each other, and staff copying data between them. An interface ends that. What it costs depends less on the number of fields than on API quality, error cases and maintenance. This article shows the cost drivers and a worked example.
What sets the price
The main cost drivers:
- Quality and documentation of both systems' APIs; without an API it gets much harder.
- Direction: only A to B, or both ways with conflict resolution.
- Data mapping: fields, statuses, units and tax rates named or structured differently.
- Volume and timing: single events in real time or large batches overnight.
- Error handling, retries on outages and alerts when something goes wrong.
No-code platform or custom code?
For standard flows between common systems, platforms like n8n, Make or Zapier are often enough: quick to set up and transparent, but with running costs per execution or user for the cloud versions. Custom code pays off for large data volumes, complex logic, special security requirements, or when one side has no standard connector. A mix often makes sense.
A worked example
Example: new orders from an online shop should go into the inventory system with customer, items and shipping method, and the shipping status should flow back to the shop. Typical effort: analysis and data mapping 4 to 8 hours, both directions 12 to 24 hours, error handling and monitoring 4 to 8 hours, testing and handover 4 to 6 hours, about 24 to 46 hours in total. At our rate of €30 per hour that's roughly €720 to €1,380. It's an experience value, not a promise; an estimate for your specific systems is more reliable.
Don't forget maintenance
Interfaces are never completely finished: vendors change APIs, fields are added, credentials expire. Plan monitoring with error alerts and a small monthly hour allowance. With us, the code lives in your repository and the credentials in your accounts, so you don't depend on us.
Frequently asked questions
- How long does building an interface take?
- A simple connection between two systems with good APIs often takes a few days. With poor documentation or no API, considerably longer.
- What happens when a vendor changes its API?
- The interface has to be adapted. Monitoring reports errors immediately so no data is lost.
- Do I own the code?
- With us, yes. Code and access are yours from day one.
Tell us the two systems and which data should go where. You get an estimate in hours and euros.
Get an integration estimate