Ask the expert: What is an API?

Featuring Calvin Leong, API Solutions Consultant, Thomson Reuters

 Calvin Leong helps firms understand what APIs are available at Thomson Reuters and how to use them.
Calvin Leong helps firms understand what APIs are available at Thomson Reuters and how to use them. He has worked with different firms to create integration and automation within their workflow using the different product APIs. He has also created connectors for different products.

What is an API?

An application programming interface (API) enables one application to use the information, functions, or features of another application.

Q  How and why are APIs used in tax, audit, and accounting?

A  To understand, let’s look at everyday examples: (1) manage staff logins across multiple applications by syncing them with Active Directory. When staff lists change in the directory, an API automatically creates or deactivates logins in various applications; (2) get, add, edit, delete, or route from a workflow application like FirmFlow. Download, upload, or modify files within document management software like GoFileRoom; (3) complete related tasks like Checkpoint Edge research or audit Confirmation from within other applications; and (4) service APIs like GoSystem Tax API can import or export values and statuses from a tax return. Even between different providers, APIs allow integration. With this connectivity, your data has a “single source of truth.” APIs are typically only available from software companies, for certain cloud-based services. If your platform can host cloud products, ask whether APIs are available for your software.

Q  Are APIs easy for every firm to implement?

A  I believe that APIs are for anyone. The key to establishing APIs is first having a use case that you need solved. Which tasks in your workflow do you think should be connected? Then, implement according to your development knowledge. Developers will find that a use case and proper API documentation are typically sufficient. Software development kits (SDKs) and Postman collections are helpful. If you’re not a developer, low-code ecosystems are useful — Microsoft Power Platform, Alteryx, and Zapier. GoFileRoom has a connector within Microsoft Power Platform and Zapier; ONESOURCE has a connector within Alteryx. These tools offer templates and require no coding language.

Q  What’s the difference between RPA and APIs?

A  These seek the same end, and they’re good to evaluate side by side. I believe that robotic process automation (RPA) and APIs are like two technologies of the past: optical character recognition (OCR) and the more accurate barcode scanning. RPA is like OCR in that it uses field names or mouse-click locations then performs a series of steps. If the user interface is redesigned, often the RPA needs updating. But with APIs, front-end changes rarely require an update. APIs typically have the advantage, and RPA is useful when APIs aren’t available.

Q  What does the future of APIs look like?

 A Thomson Reuters has adopted a platform strategy, which inherently includes APIs. More APIs can be released faster under this strategy. For example, Onvio is a cloud-based platform. Other platforms such as ONESOURCE, GoSystem Tax RS, GoFileRoom, and FirmFlow have already released external APIs. For more information, visit

Thomson Reuters tax and accounting APIs

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