Additional Resources

There are many great tools for working with web APIs and other web traffic.

Fresnel does not license, endorse or warrant any of these tools, however they are documented here as a suggested option for users trying to diagnose errors or performance issues.

Fresnel does not license any of these tools for client use. At the time of writing, all tools mentioned here offered a zero cost edition of their product. Please read the necessary license requirements for each tool.

The use of these tools can assist users in identifying whether a particular issue is due to the way the API is being called, the API itself not working or if there is a problem with the client application.

Postman

https://www.postman.com/

Postman offers many features, however its primary use in this context is as a stand-alone API client. Users can create collections of API requests that can be saved and re-executed while specifying different endpoints, query parameters and headers to test the API calls.

Postman will display the APIs result code and the returned results in nicely formatted JSON. In addition, Postman also displays the duration (length of time) and the payload size to help understand any performance concerns.

Postman is particularily useful in helping users unfamiliar with working with REST APIs to test API calls in a standalone environment as well as testing calls outside of more complex tools.

In addition to the Postman app, Postman also offers a great Learning Center to help walk people through both general API concepts as well as the use of their tool.

See https://learning.postman.com/docs/getting-started/introduction/

Telerik Fiddler

https://www.telerik.com/fiddler

Fiddler can also be used as an API client in a similar way to Postman, however it does lack a few helpful features such as the use of variables and scripts.

Fiddler's primary use is as an API "inspector". Fiddler can intercept web API calls on your local machine and display the same information as Postman such as the called API endpoint, duration, result code, headers, query parameters, and results.

However, Fiddler is useful in helping to capture and understand requests sent from other tools (such as Excel or Power BI) to better understand potential performance issues, such as:

1. Have multiple requests been sent to the server?
2. What order are the requests being sent in?
3. Are the responses getting paged?
4. How many round trips to the server are being made to get all pages?
5. What is the size and duration of each page? (useful for troubleshooting timeout errors)
6. Are the correct query paramanters and headers getting passed to the request?

Identifying and reproducing issues in these tools can often be quicker and easier than trying to fix them in other 3rd party tools which often lack extensive diagnostic capabilities.