# Create your first API: "Hello World!"

To create an API, follow the steps.

* To go to the API section, click “API” under the “APIs and Integration” menu on the left-side panel.

{% embed url="<https://media.langstack.com/documentation/media/images/code/training_manual/chapter_4/ch4apimenu.png>" %}

* To create an API, click the \[+ API] button to create a new API.

{% embed url="<https://media.langstack.com/documentation/media/images/code/training_manual/chapter_4/ch4addapi.png>" %}

* By default, the “Details” tab is selected. To label the API:&#x20;
  1. Name the API "gettingstartedHelloWorld".&#x20;
  2. To select the API method, click on the “API Method” drop-down list. For this exercise, select the API method “GET”.&#x20;
  3. Optionally add a description for the API.

{% embed url="<https://media.langstack.com/documentation/media/images/code/training_manual/chapter_4/ch4hwnamedetails.png>" %}

* Add the API group name "gettingstarted". ([See the steps here](/welcome/get-started/learn-langstack/introduction-to-rest-api/api-group-name.md#how-to-select-or-create-an-api-group))&#x20;

{% embed url="<https://media.langstack.com/documentation/media/images/code/training_manual/chapter_4/ch4hwgrpname.png>" %}

&#x20;

* The API URL is generated.

{% embed url="<https://media.langstack.com/documentation/media/images/code/training_manual/chapter_4/ch4hwurl.png>" %}

* In the “Inputs & outputs” tab, a “Response body” is created by default with the response object "defaultResponseJsonBody".

{% embed url="<https://media.langstack.com/documentation/media/images/code/training_manual/chapter_4/ch4hwrespbody1.png>" %}

* To define the response object, expand the Response body and add the sample JSON {"message":"string"}.

{% embed url="<https://media.langstack.com/documentation/media/images/code/training_manual/chapter_4/ch4hwrespbody2.png>" %}

* To define the Actions, go to Code tab. An Action box is already created by default.

{% embed url="<https://media.langstack.com/documentation/media/images/code/training_manual/chapter_4/ch4hwactionbox.png>" %}

* In the "Code" tab of the Action box, an Action "API respond" is already added by default with Response body selected as "defaultResponseJsonBody".

{% embed url="<https://media.langstack.com/documentation/media/images/code/training_manual/chapter_4/ch4hwapirespond.png>" %}

* To add a new Action, click (+).

{% embed url="<https://media.langstack.com/documentation/media/images/code/training_manual/chapter_4/ch4hwapirespondplus.png>" %}

* Drag the new Action upward to place it above API Respond.\
  (Any Action after API Respond is not executed.)

{% embed url="<https://media.langstack.com/documentation/media/images/code/training_manual/chapter_4/ch4hwapirespondnewact.png>" %}

* Define the new Action as follows:

  1. Select Action as "Update variable".
  2. Select Source as Response>defaultResponseJsonBody>message. It is displayed as Response.defaultResponseJsonBody.message.
  3. Enter Value as "Hello World!" (without quotes) and hit Enter. The text will be enclosed in a bubble.

  <figure><img src="https://media.langstack.com/documentation/media/images/code/training_manual/chapter_4/ch4hwuvrespmsg.png" alt=""><figcaption></figcaption></figure>
* To save the API click the \[Save] button.

<figure><img src="https://media.langstack.com/documentation/media/images/code/training_manual/chapter_4/ch4hwsaveapi.png" alt=""><figcaption></figcaption></figure>

* To publish the API, click the \[Publish] button.

<figure><img src="https://media.langstack.com/documentation/media/images/code/training_manual/chapter_4/ch4publishapi.png" alt=""><figcaption></figcaption></figure>

{% hint style="info" %}
The created API must first be published in order to be visible to an API gateway.
{% endhint %}

* Once the API is published, the default API gateway can be added; go to the “Details” tab. \
  Add an API gateway "gettingstartedHelloWorld".  (if unsure how to add an API gateway, [see steps here](/welcome/get-started/learn-langstack/basics-and-essentials/how-to-work-with-an-api-gateway.md).)

![](/files/BbFjH78PlU4XJfIdX0jb)

* Click the \[Save] button again.
* To make the API publicly available, it must be enabled. Toggle the “Disabled” button and it will change to “Enabled”.

{% embed url="<https://media.langstack.com/documentation/media/images/code/training_manual/chapter_4/ch4enableapi.png>" %}

* Use the created URL to see how the API works by pasting it into the browser. The text "Hello World!" will be displayed.

![](/files/MqyggnXr7hD9MwayuDFy)


---

# Agent Instructions: Querying This Documentation

If you need additional information that is not directly available in this page, you can query the documentation dynamically by asking a question.

Perform an HTTP GET request on the current page URL with the `ask` query parameter:

```
GET https://docs.langstack.com/welcome/get-started/learn-langstack/introduction-to-rest-api/create-an-api.md?ask=<question>
```

The question should be specific, self-contained, and written in natural language.
The response will contain a direct answer to the question and relevant excerpts and sources from the documentation.

Use this mechanism when the answer is not explicitly present in the current page, you need clarification or additional context, or you want to retrieve related documentation sections.