How We Build System Integrations for Our Clients

Introduction

One of the most common requests we get from clients is connecting their existing tools. They use Slack for communication, Azure DevOps for development, a CRM for sales, and an accounting package for invoicing. But nothing talks to each other.

At MG Software, building these integrations is what we do best. In this article, we share our approach and the lessons we have learned from connecting hundreds of systems for our clients.

Why Businesses Need Custom Integrations

Off-the-shelf integration tools like Zapier or Make work great for simple tasks. See our comparison of n8n vs Zapier if you are evaluating automation platforms. But when your business has unique workflows, you need something tailor-made.

We see this pattern constantly: a client has outgrown their Zapier setup. They need real-time sync instead of polling every 15 minutes. They need error handling that does not silently fail.

Our Integration Architecture

"The average enterprise uses 1,061 applications, yet only 29% of them are integrated."

— MuleSoft 2023 Connectivity Benchmark Report

Every integration project starts with mapping the data flow. What systems are involved? What data needs to move? In which direction? How often?

We use a three-layer architecture: a webhook or API layer for receiving events, a processing layer for transformations and business logic, and a delivery layer for pushing data to the target system.

Real Example: CRM to Project Management

A recent client had their sales team in HubSpot and their development team in Azure DevOps. When a deal closed, someone had to manually create a project. This took 30 minutes per project and things got forgotten.

We built an integration that automatically triggers when a deal moves to "closed-won" in HubSpot. It creates a project in Azure DevOps, assigns team members, and sends a Slack notification. What used to take 30 minutes now happens instantly. For more examples like this, see our custom CRM system examples and business process automation examples. If you are looking for tools to manage this kind of workflow, check our overview of the best project management tools.

Handling the Hard Parts

The technical challenges in integration work are the edge cases. What happens when Slack rate-limits you? When the CRM API changes without notice? When two systems update the same record simultaneously?

We solve these with battle-tested patterns: exponential backoff for rate limits, webhook signature verification for security, idempotency keys to prevent duplicates, and comprehensive logging and monitoring. Choosing the right observability stack is critical. Explore our guide to the best monitoring tools.

From Exact Online to Mollie: The Connections We Build Most

Some integrations come back so often that we have refined them into a near-standard approach. Exact Online tops the list: Dutch companies want their custom application to push invoices, customers and payment statuses into the bookkeeping automatically, instead of someone retyping them every Friday. Mollie and Stripe follow closely, for everything from webshop payments to automatic payment reminders. And email deserves a mention of its own: converting a shared mailbox into structured tickets or orders removes a surprising amount of manual work in almost every company we visit.

These recurring patterns benefit you directly. Because we have already solved the OAuth flows, rate limits and sandbox quirks of these platforms, a standard Exact Online or Mollie connection typically takes one to two weeks instead of the four you might expect. See our software integration services and the dedicated Exact Online integration page for how we approach each platform.

What an Integration Project Looks Like Week by Week

Week one is mapping. We sit down with the people who actually use both systems and draw out every data flow, including the exceptions everyone forgets: credit notes, cancelled orders, customers that exist twice with slightly different names. This week determines the success of the whole project, because an integration that handles 95% of cases and silently drops the rest is worse than no integration at all.

Week two covers the core connection in a sandbox environment, so no production data is at risk. Weeks three and four are where reliability is earned: testing with real historical data, deduplication, error alerting, and finally a supervised go-live where the old and new process run side by side for a few days. Budget-wise, most standalone integrations land between 5,000 and 15,000 euros depending on the systems involved; our project calculator gives a first estimate for your specific combination.

Conclusion

System integration is the backbone of modern business operations. When your tools talk to each other, your team spends time on real work instead of copying data between screens.

At MG Software, we have built integrations for businesses across the Netherlands and beyond. Whether you need to connect two systems or orchestrate a dozen, we would love to hear about your challenge.