Quick answer: API integration means connecting your website to other software, such as your CRM, accounting package, stock system or booking tool, so information passes between them automatically instead of being typed in by hand. Most modern business software offers an API for this. Simple links can be set up with a connector such as Zapier; integrations that need more control, higher volumes or connection to your own systems are usually built by a developer. Good planning covers which data moves, in which direction, how often, and what happens when something fails.
Most businesses end up with a website in one place and the rest of their operations somewhere else. Orders arrive on the site and get retyped into the accounts. Enquiries come in by email and get copied into the CRM. Stock levels are updated in a spreadsheet and then on the shop. Each copy is a chance for a delay or a mistake, and together they take up hours every week. Integration is how you join those pieces up.
What an API does
An API (application programming interface) is a set of rules that lets one piece of software ask another for information or tell it to do something. When your website sends a new order to your accounting software, it is calling that software’s API: “create an invoice with these details”. When your shop checks stock, it is asking another system’s API: “how many of this item do you have?” If you want the basics in more depth, our explainer on what an API is covers them.
Most web APIs today follow the REST style, send data as JSON, and use secure HTTPS connections. They usually require a key or a login token, so only authorised systems can use them.
Common website integrations
Website to CRM
Every enquiry form submission creates or updates a contact in your CRM, such as Salesforce, HubSpot, Zoho or Capsule, with the source, the page they came from and the service they asked about. Sales staff see it straight away and nothing gets lost in an inbox.
Shop to accounting
Orders from your online shop create invoices or sales receipts in Xero, QuickBooks Online or Sage, with the right tax codes. Refunds create credit notes. Your accounts stay up to date without a weekly copying session.
Stock and inventory
If you sell in a physical shop and online, or on more than one marketplace, stock levels need to stay in step. An integration with your inventory or point of sale system updates the website when something sells elsewhere, so you do not sell items you no longer have.
Booking and scheduling
Bookings made on the site go straight into your practice management or diary system, with confirmations sent automatically. Availability shown on the site comes from the same source.
Email marketing
New customers and subscribers are added to the right list in MailChimp or Campaign Monitor, tagged by what they bought or asked about.
Payment providers
Payment gateways such as Stripe, PayPal and Sage Pay are themselves API integrations. The site sends the payment request and receives back whether it succeeded.
Shipping
Orders are sent to a courier or fulfilment service, labels are printed, and tracking numbers come back to the order and the customer’s email.
Ways to build an integration
Ready made plugins
If your site runs on WordPress or WooCommerce, there is often a plugin that connects to the system you use. These are quick to set up and cheap. The trade off is that you get the plugin’s idea of how the data should map, and you depend on the plugin’s developer to keep it working.
Connectors such as Zapier
Zapier links hundreds of web apps without code. A trigger in one app, such as a new form entry, runs an action in another, such as creating a contact. It suits low to moderate volumes and simple flows. Our Zapier guide explains how to set one up.
Custom integration
A developer writes code that talks directly to each system’s API. This is the right choice when:
- No plugin or connector does what you need.
- You need to connect to your own in house software or database.
- Volumes are high, or speed matters.
- The data needs reshaping, checking or combining along the way.
- You want full control over error handling and logging.
If the system you need to connect to has no API, a developer can sometimes build one for it. Our page on custom API development covers that side.
How an integration project runs
1. Map the data
List exactly what needs to move. For each item, note:
- The source system and the destination system.
- The fields, and how they match up. Your shop might store first and last name separately while the CRM has one field.
- The direction: one way, or both ways.
- What counts as the same record. Email address? Customer number?
This step is where most problems are prevented. It is also where you find out that two systems define a “customer” differently.
2. Decide on timing
Does data need to move instantly, or is every hour, or once a night, enough? Instant updates usually use webhooks, where one system notifies the other the moment something happens. Scheduled updates use a regular job that checks for changes. Instant is not always better: it can be more complex and it hits API limits faster.
3. Check the APIs
Read the documentation for each system. Look at what data the API exposes, how you authenticate (many use OAuth 2.0 or API keys), how many requests you are allowed per minute or per day, and whether there is a test or sandbox account.
4. Plan for failure
Every integration will fail sometimes. A service goes down, a password changes, a field is left empty. A good integration:
- Retries failed requests sensibly.
- Logs what it sent and what came back.
- Alerts someone when something keeps failing.
- Never loses data quietly, for example by storing orders it could not send and trying again later.
5. Build and test
Test with real examples, including awkward ones: long names, special characters, refunds, cancelled orders, duplicate customers. Run the integration alongside the manual process for a short time and compare the results.
6. Document and monitor
Write down what the integration does, which accounts and keys it uses and who to contact when it breaks. Check the logs regularly for the first few weeks.
Things to watch out for
- API changes. Software providers update their APIs and retire old versions. Integrations need occasional maintenance.
- Security. Store API keys securely, never in public code, and give each integration only the permissions it needs.
- Personal data. Moving customer data between systems is still processing personal data. Make sure each system is one you are comfortable holding it, and that your privacy policy reflects it.
- Duplicates. Without a clear matching rule, integrations can create the same customer twice. Decide your rule early.
- Ownership. Someone in the business should know the integration exists and what to do if it stops.
FAQ
How long does an API integration take?
A plugin or Zapier connection can take an afternoon. A custom integration between two well documented systems might take days to a few weeks, depending on the data and the error handling needed.
What if my software has no API?
Some systems can export and import files on a schedule, which can be automated. Otherwise, it may be worth asking the supplier, or considering a system that does offer one.
Will integration slow my website down?
It should not, if built well. Slow tasks can run in the background so visitors are not left waiting.
Ready to connect your systems?
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