> For the complete documentation index, see [llms.txt](https://docs.langstack.com/welcome/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.langstack.com/welcome/get-started/learn-langstack/introduction-to-rest-api/exercise-1-get-rest-api-and-return-response-object/step-2-test-the-api.md).

# Step 2: Test the API

To test the API, proceed as follows.

* To test the API, click on the \[Test] button.

<figure><img src="https://media.langstack.com/documentation/media/images/code/training_manual/chapter_4/ch4nocalctestapi.png" alt=""><figcaption></figcaption></figure>

* In the Query strings section, the Query strings “Number1” and “Number2” display initialized values. \
  To define the operator for addition, enter the value for the and the “operation” as “Add.” \
  Click the \[Test API] button.

{% embed url="<https://media.langstack.com/documentation/media/images/code/training_manual/chapter_4/ch4nocalctestapi2.png>" %}

* The result of the addition will be visible in the “Body.”

{% embed url="<https://media.langstack.com/documentation/media/images/code/training_manual/chapter_4/ch4nocalctestresult.png>" %}

* To test the API in the browser, add the URL in the browser and enter the values in Query strings as per the link below. The result will be displayed in the browser.

<figure><img src="https://media.langstack.com/documentation/media/images/code/training_manual/chapter_4/ch4nocalcapiinbrows.png" alt=""><figcaption></figcaption></figure>