What an API is, for business owners
An API is how one piece of software asks another for something, without a person in between. Knowing that much is enough to ask your vendor the right questions.
· 3 min read · For owners and managers of small firms, shops, schools and clinics who buy or commission software
Your billing vendor says the new app will "talk to Tally by API". Your WhatsApp partner asks for "API access". The GST e-invoice portal has an "API developer's portal". You nod, but you are not sure what you are agreeing to or paying for. Here is the short version.
What an API is, in plain words
API stands for application programming interface. It is a fixed set of requests that one system agrees to answer for another. Think of the counter at a bank. You do not walk into the vault. You fill a slip in a set format, hand it over, and get a clear answer back. An API is that counter, but for software.
The difference from a person copying data is simple. With an API, the order on your website reaches the warehouse system in a second, the same way every time, at 2 a.m. too. No retyping, no missed rows.
Where you already use one
- GST e-invoicing. When your billing software gets an IRN (the invoice reference number) without you opening the portal, it is calling the government's e-invoice API.
- WhatsApp messages from a business number. Order updates and reminders go out through the WhatsApp Business Platform's Cloud API, not someone typing on a phone.
- Payment links. Your payment gateway tells your system "paid" or "failed" through an API, so the order updates itself.
When it is worth it, and when it is not
An API connection is worth building when the same data is typed into two places every day, when mistakes in that copying cost you money, or when speed matters to the customer. It is not worth it for a report you prepare once a month. A clean export to Excel is cheaper and easier to fix.
Also remember that an API is a door into your data. If it is left open, anyone who finds it can walk in. OWASP, a respected security community, keeps a list of the most common API mistakes. The top one is a system that lets one customer see another customer's records just by changing a number in the request.
Five questions to ask any vendor
- Which systems will this connect to, and does each one offer an official API? Avoid tools that copy data by "reading the screen".
- Who owns the API keys (the passwords one system uses to call another), and can we change them if a staff member leaves?
- What happens when the other side is down? Are requests retried, or lost quietly?
- Will we see a log of what was sent, when, and whether it worked?
- If we change vendors later, can the new team use the same API, or is it locked to you?
If the answers are vague, the connection will be fragile. For more on the basics, see security basics for your app and moving from Excel to a real system.
How we can help
We build and connect business software: billing to Tally, orders to WhatsApp, apps to GST e-invoicing and payment gateways. We build each connection with its own keys, logs and retries, and hand the documentation over to you. You can read about this work on our services page. If two of your systems are being kept in step by hand, we are happy to look at it with you. Just talk to us.
