An Integration and API Guide for Businesses

In a business the same data usually lives in more than one place: orders in the e-commerce panel, invoices in the accounting program, customer details in a spreadsheet. When these systems don't talk to each other, a person does the carrying in between, and that's where errors start.

What is an API, what does it add to my business?

An API is an interface defined so that two pieces of software can ask each other for data and send it. Its practical counterpart: when an order is created on your site, the invoice drops into the accounting program by itself, the tracking number comes automatically from the courier company, or stock information updates in two systems at the same time.

The gain comes from two places. First, time: manual data entry disappears. Second, and more important, accuracy: when the same information is entered by hand in two places it diverges sooner or later, and the argument about which is correct begins.

Which integrations really pay off

Not every connection is worth building. Decide with this criterion: transaction frequency × cost of error.

For a transfer done three times a month that's easily corrected even if wrong, integration is costly. On the other hand, a transfer repeated fifty times a day, or one that reaches the customer when wrong (orders, stock, invoices), pays for the integration within a few months.

The four connections that pay off most often are: e-commerce with accounting, site form with CRM, stock with marketplace, shipment tracking with customer notification.

Types of integration

• Ready-made connector. A module offered by the vendor between two popular systems. The cheapest and fastest route; no room for flexibility.
• Middleware service. Third-party platforms that connect systems to each other. Set up without writing code, monthly fee, falls short with complex rules.
• Custom development. A connection written using the APIs of the two systems. The most flexible; the only realistic option if your workflow is unique.

The order should be this too: first check whether a ready-made connector exists, if not evaluate a middleware service, and if that's not enough do custom development.

What determines the cost

The difference between integration quotes usually comes from these four items:

1. Does the other system have an API, and is it documented? Working with an undocumented or closed system doubles the time.
2. Is the transfer one-way or two-way? Two-way transfer also requires defining conflict rules.
3. How much data, how often? Real-time transfer and a daily batch transfer require different structures.
4. What happens on failure? The real work is here: when the connection drops, data must not be lost, it must be retried and someone must be notified.

The fourth item is the one most often skipped in quotes and the one that causes the most problems later.

What must be decided from the start

• Which system is the source of truth? If the same information exists in two places, which will be accepted as correct? An integration built without answering this question stops at the first conflict.
• Which fields will be transferred? Not every field needs moving; moving unnecessary data increases both risk and maintenance burden.
• How will authentication work? Where will the keys be stored, who can access them, who renews them when they expire.
• Is there a test environment? Being forced to test with live data is the biggest risk in integration projects.

Without monitoring, an integration is half done

A connection that's been set up runs silently and stops silently. Most businesses notice the integration has broken days later, with the question "why aren't the invoices coming".

That's why every integration must have three things: a log of failed operations, a retry mechanism and a notification when errors exceed a certain threshold. These raise the development cost somewhat, but this is the part that makes the system truly reliable.

A short note on data formats

The most common format for exchanging data between systems is JSON. When examining an integration problem you often need to make the raw data you receive readable and see whether the fields are coming through correctly.

Likewise, checking the contents of a credential (token) sent to a service or decoding an encoded piece of text are common tasks. No complex setup is needed for these.

When not to integrate

If the process hasn't settled yet, integration is premature. Putting a workflow that's still changing into code creates a development cost with every change.

Likewise, connecting a system you plan to replace very soon is a waste. Decide on the system first, then connect it.

The stages of an integration project

A healthy integration project follows this order, and each step has an output:

1. Process map. Which data goes from where to where, on which trigger. When this step is skipped, questions keep coming up during development.
2. Field mapping. The correspondence between the fields in the two systems. "Customer name" may be a single field in one system and first name plus last name in the other.
3. Setup in the test environment. Without touching live data.
4. Controlled go-live. First with a small data set, verifying by hand.
5. Monitoring and handover. Who receives error notifications, who intervenes when a problem arises.

The second item is the one most underestimated in quotes; time estimates given before the field mapping is clear almost always slip.

Rate and limits

Every API has a limit on how many requests it accepts in a given period. When this limit is exceeded, requests are rejected and the integration silently starts losing data.

That's why two things must be discussed when designing the transfer: real-time or batch, and what happens when the limit is hit. Batch transfer (hourly, for example) is enough for most jobs and is both cheaper and more resilient. Real-time transfer is needed only where delay is a real problem — like stock and prices.

The security side

An integration opens a permanent door between two systems. The API keys that are the key to that door must not be embedded in code, must not enter version control and must be generated with the narrowest possible permissions.

Giving a connection that only needs to read orders the permission to delete customers is a common and unnecessary risk. Who generated the keys, when, and who renews them when they expire must also be decided from the start.

What to receive when the integration is finished

When the project closes you should have: a diagram showing which data flows where, information on where the keys used are stored, who receives the notification on failure and how the system is stopped and restarted.

Without these documents the integration turns into a black box. When you part ways with the team that built it, you're left with a connection that works but nobody understands; at the first failure the only option is having it rewritten from scratch.

The difference between webhooks and polling

Two systems notify each other in two ways. In the polling method your system asks "is there anything new" at set intervals; it's simple to set up but creates delay and generates unnecessary requests.

In the webhook method the other system notifies you the moment the event happens. It's faster and more efficient; in return, there must be a continuously reachable address on your side and the incoming notification must be verified as really coming from that system. Webhooks are preferred whenever possible.

To format JSON output, decode encoded data or view the contents of a credential you can use the tools on the Developer Tools page. Corporate integration and automation work is within the scope of our services.