A business owner's guide to APIs

What an API actually is

You'll have heard the word. You'll have seen it on quotes ("API integration: 4 hours") and in conversations with software people who assume you know what they mean.

So, plainly: an API is a controlled doorway into a piece of software. It lets one system ask another system for information, or tell it to do something — without a human in the middle, copying and pasting.

A useful analogy: think of a restaurant. The kitchen is a software system — let's say it's Xero, or your warehouse management package, or your CRM. You don't go into the kitchen and rummage around. You sit in the dining room and a waiter takes your order. The waiter is the API. They know what's available on the menu, how to ask for it, and how to bring it back to you.

Different kitchens have different menus. Xero's menu has things like "list invoices for this customer", "create a new bill", "tell me what's outstanding". A courier's menu has "give me a label for this parcel", "where is this delivery now?". The menu is the API.

That's it. That's the whole concept. Everything that follows is just what happens when you start using one.

Three places APIs change a business

1. Inbound — your customers integrating with you

If you sell to other businesses, the larger ones increasingly expect to talk to you through software, not email. They want to:

• Place orders from their own purchasing system without a human typing them into yours
• Get live stock and pricing
• See where their delivery is
• Pull invoices straight into their accounts package

If you have an API, that just happens. The customer's system asks yours; yours answers; nobody re-keys anything. Their procurement team likes you better and your office stops drowning in "where's my order?" emails.

If you don't, you have one of two outcomes. Either the customer goes elsewhere because their internal team can't justify the manual overhead, or you absorb that overhead — staff in your office answering those emails forever.

A good business API is increasingly something B2B customers expect to see on a tender response. Not having one is starting to cost work.

2. Outbound — you integrating with suppliers and tools

The other direction is just as important. Almost every system you already pay for — accounting, CRM, courier, payroll, ERP, payment processor, helpdesk — has an API.

That means the data sitting in one can move into the other. Without somebody copying it.

A few concrete examples we've built recently:

• Orders raised in a bespoke job system automatically appear as draft invoices in Xero, with the right nominal codes, the right VAT, the right customer
• A courier API generates labels overnight and writes the tracking numbers back, so the customer service team doesn't have to log in to three different couriers' websites
• A bank feed reconciles against expected payments overnight, flagging only the ones that don't match
• New leads in the CRM check the credit reference agency's API and tag themselves before the salesperson even sees them

Every one of those replaces a job somebody used to do by hand. Quietly, overnight, unglamorously. Worth thousands a year, usually. Sometimes a lot more.

If you're paying someone to do something repetitively, there's a better way to do it.

3. Internal — bridging your own systems

This is the one most business owners haven't thought about, and it's often the highest-value of the three.

You probably have software that has grown up in pieces. The accounts system someone bought in 2014. The custom Access database with the customer history. The spreadsheet that nobody fully understands but everyone relies on. The CRM the sales team keeps in their own world.

Each of those holds a piece of the truth about your business. None of them holds all of it. So your team makes up the gap — they hold the picture in their heads, and they keep the pieces in sync by hand.

APIs are how those internal systems start talking to each other. Sometimes that means we add an API to a system that didn't have one (yes, that's a thing — even for old custom-built systems). Sometimes it means we build a small bespoke layer that quietly pulls from all of them and gives you one screen with the whole picture.

This is where an outside-in perspective matters. From the inside it looks like the way it's always been. From outside, it looks like four people copying numbers between four screens — and an obvious place for software to do that work instead.

What good looks like

A few things to look for, whether you're commissioning an API or evaluating one a vendor offers you:

• It does one thing well per endpoint. "Create an order", "get the status of this delivery", "list invoices for this customer". Small, named jobs.
• It's documented in a way a developer can read on a Wednesday and use on a Thursday. If your supplier's API documentation is a 60-page PDF nobody can find, that tells you something.
• It handles failure gracefully. Real-world data is messy. Good APIs tell you exactly what went wrong, in language you can act on.
• It doesn't change underneath you. The business equivalent of moving the light switches every Friday. Look for proper versioning.
• Authentication is sensible. Modern APIs use API keys or OAuth. If anyone wants you to email a username and password, walk away.

You don't have to evaluate any of this yourself. But knowing the shape of "good" makes the conversation with your developer or vendor a lot more useful.

Where to start

You don't need to "do APIs" as a project. You need to spot the place where information is currently being moved by hand, and ask: could the systems do that themselves?

Some honest signals you're ready:

• A member of your team spends half a day a week copying data between two systems
• Customers regularly ask "can your system talk to ours?" and the answer is no
• You can't get a single accurate picture of the business without three logins and an export

If any of those sound familiar, the next step isn't a six-figure integration project. It's an honest conversation about which one piece of plumbing would change the most.

That's the kind of conversation we have most weeks. If it sounds like one you'd like to have, say hello.