Most new business apps do not start on a blank slate. They have to talk to an old ERP, an accounting package, a government portal or a third-party service that nobody wants to touch. In product work for enterprises, SMEs and government bodies, weak integration and disconnected departments are among the most common problems we see, so integration deserves its own plan from day one.
Before you write any code
- Map the systems and owners. List every system the new app must read from or write to, and who can approve changes on each side.
- Decide where each piece of data lives. One system should be the source of truth for customers, another for invoices, and so on. Duplicated masters cause most sync bugs.
- Pick the integration style per system. A clean REST API, a scheduled file export, or a database view. Older systems often only support the last two.
Design it so it can change
- Keep integrations in their own module. An adapter layer between your app and each external system means a replacement later touches one module, not the whole codebase.
- Expect failures. Add retries, timeouts and a queue for writes so a slow legacy system does not freeze your UI.
- Log every exchange. When numbers do not match between two systems, request and response logs settle the argument quickly.
Ship it safely
- Put integration tests in the CI/CD pipeline with stubbed versions of each external system, so a change on your side cannot silently break the link.
- Test performance with realistic volumes, not ten sample records.
- Treat credentials as secrets. Keep API keys out of the repo and give each integration the least access it needs.
- Give managers a dashboard with role-based views of sync status, so problems are seen before users report them.
More detail: how Affix Center approaches API integration and product engineering
Written by the team at Affix Center, an IT services company in Lower Parel, Mumbai.
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