# Calling APIs on Blockflow

Once you have created an API on Blockflow, you can invoke it using the following endpoint formats:

1. Using API ID:

   ```
   https://api.blockflow.network/api/<apiId>
   ```
2. Using API Slug and Project ID:

```
https://api.blockflow.network/api/<apiSlug>?projectId=<projectId>
```

### **API ID and Project ID**

You can find the `apiId` and `projectId` on your Blockflow dashboard. These identifiers are unique to each API and project, respectively.

* `apiId`: The unique identifier assigned to your API.
* `projectId`: The unique identifier assigned to your project.

### **API Slug**

The `apiSlug` is a user-defined, URL-friendly name for your API. You specify the API slug during the API creation process. It allows you to use a more descriptive and meaningful name in the API endpoint URL.

### **Examples**

Let's say you have an API with the following details:

* API ID: "123"
* Project ID: "456"
* API Slug: "test"

You can call the API using either of the following endpoints:

1. Using API ID:

   ```
   https://api.blockflow.network/api/123
   ```
2. Using API Slug and Project ID:

   ```
   https://api.blockflow.network/api/test?projectId=456
   ```

### **Authentication**

When calling your API, make sure to include the necessary authentication credentials as specified in your API configuration. This will include API keys, tokens, or other authentication mechanisms.

### **Query Parameters and Request Body**

Depending on your API design, you may need to pass additional query parameters or include a request body when making API calls. Refer to this guide to understand the required parameters and request format.

{% content-ref url="how-to-write-api-logics" %}
[how-to-write-api-logics](https://docs.blockflow.network/guides/creating-an-api/how-to-write-api-logics)
{% endcontent-ref %}

### **Error Handling**

If an error occurs while calling your API, Blockflow will return an appropriate HTTP status code along with an error message in the response body.&#x20;

### **API Documentation**

To provide a better developer experience, it's recommended to document your API endpoints, request/response formats, and any authentication requirements. You can use tools like Swagger or Postman to create and host your API documentation.

### **Example API Call**

Here's an example of making an API call to your Blockflow API using JavaScript and the Fetch API:

```javascript
fetch('https://api.blockflow.network/api/123', {
  method: 'GET',
  headers: {
    'x-api-key': '<your-api-key>',
    'Content-Type': 'application/json'
  }
})
  .then(response => response.json())
  .then(data => {
    // Handle the API response data
    console.log(data);
  })
  .catch(error => {
    // Handle any errors that occurred during the API call
    console.error('Error:', error);
  });
```