An application programming interface (API) is a way for two or more computer programs to communicate. It is software which offers a service to other software.



In practice, an API is a separate project which provides access to your services and data. This can be consumed by clients such as a website, a mobile application, or your customers.



Companies make their services available to developers via their APIs. This means you can integrate familiar software into your automated processes.



An example of a great API is the Xero accounting API. It is possible to replicate all of the functionality in the standard version of Xero using code. This means you can download your invoices or generate documents and upload and attach them to your invoices. You could create a custom document using data from your company, send it off for signing, add any further info with text, and then upload it to Xero.



Another example is Zoopla - it is possible to upload properties and change their status via the API. This would be useful for a prop-tech startup creating a property portal or mobile app.



One of the main advantages of building or consuming an API is that those who are using the API do not need to know about the implementation details. They can read the documentation and get expected outputs.



It is possible to integrate numerous API’s into your software project.



E.g.



Twilio - SMS notifications



MailJet - Email notifications (reset password etc)



Auth0 - Login services for your site



Google Docs API - Write out reports to Google Docs and save them



Stripe - integrate payment pages into your site



Youtube/Instagram/Twitter - highlight your social media posts on your app