How to check a developer has done the integration you need

You've hired a developer, work has been underway, and now you need to verify they've actually delivered what you asked for. Or maybe you're partway through a project and want to check progress. The risk isn't incompetence alone—it's silent misalignment. A developer might have built *something*, but if it's not the integration *you* need, you've paid for the wrong work.

The core question is: how do you move past "they say it's done" to knowing it actually works and solves your problem?

Running tests on what they've built

Before you accept or pay for the final delivery, you need to see the integration in action—not just hear about it. Ask the developer to walk you through a live test, or better yet, to give you access to a staging environment where you can test it yourself.

Start with the basics. Can you successfully authenticate—that is, does your system connect to the API or service they've integrated with? Send a test transaction or data point through the integration and verify it arrives in the other system exactly as it should. If the integration involves payments, pull up a test charge and confirm the amount, reference and timestamp all appear correctly on both sides. If it's CRM data, create a dummy contact in your system and watch it sync to the external platform; then update that contact and confirm the change propagates back.

Ask for documentation or a test log showing the developer has already run these checks themselves. Any developer worth hiring will have done this and will have records. If they brush off your request to see proof, that's a red flag. They should also tell you what edge cases or error scenarios they've tested—what happens if the connection drops, if a field is blank, if the API returns an unexpected response. A robust integration anticipates failure modes.

Request the exact list of data fields or parameters the integration handles. Cross-reference this against your original scope. If you agreed to sync customer email, phone and purchase date, but they've only built email and phone, that's incomplete work—and you need to know before you sign off. Insist on seeing their test results in writing, even if it's just a checklist or screenshots.

Proof, references and what to ask them

Ask the developer for a technical reference—someone who has used them for a similar integration and can speak to whether the work held up over time. This is different from a general character reference. You want someone who can tell you whether the integration stayed stable, whether the developer was responsive when issues emerged later, and whether they handed over clear documentation so the client's own team could maintain it.

When you call that reference, ask specific questions. Did the integration work as promised on day one? Did it break when the API provider made updates? How responsive was the developer when something needed fixing? Did they provide clear instructions for troubleshooting, or did you need them to bail you out every time? This conversation will tell you far more than any portfolio.

Request all code documentation, API keys (securely handed over) and any configuration files so you have a complete record of what was built. A professional developer will have already prepared this. Ask them to explain the integration's weak points—there are always some. Are there rate limits on the API that could be hit during peak usage? Does the integration depend on a specific field format that could cause problems if your data changes? This isn't weakness; it's honesty, and it tells you they understand what they built.

Get a written summary of what the integration does, what it doesn't do, and what maintenance or monitoring might be needed going forward. This becomes your reference when something behaves oddly six months from now.

Before you close the project, run a full end-to-end test yourself with real or realistic data. Don't rush. A developer can build something that works once and falls over under actual load or with edge-case data. If it passes, get everything in writing—acceptance notes, test results, documentation and contact details for future support.

When you're ready to hire someone new or need to verify a developer's work, Strove's verified freelancers come with review histories and the ability to request references directly within the platform, making it easier to confirm they've delivered integration work that actually works.