> For the complete documentation index, see [llms.txt](https://docs.developers.symphony.com/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.developers.symphony.com/ext-apps/overview-of-extension-api/extension-api-services.md).

# Extension API Services

The Client Extension API uses services for communication between your application and the Symphony client. The Client Extension API provides a set of services that your application can leverage to extend the Symphony Client and to create custom workflows and experiences.

## Client Extension API Services:

The Client Extensions API provides the following remote services:

### **Modules Service**

Use the `modules` service to create application-specific modules**:**

{% content-ref url="/pages/-MJPWunEjIsES4QbtHxm" %}
[Modules Service](/ext-apps/overview-of-extension-api/extension-api-services/modules-service.md)
{% endcontent-ref %}

### **Applications-Nav Service**

The Applications navigation section is found at the bottom of the left-hand sidebar of the Symphony client workspace. Use the `applications-nav` service to create a navigation item for your application**:**

{% content-ref url="/pages/-MJPWunHUlEXYc1r7d-0" %}
[Applications-Nav Service](/ext-apps/overview-of-extension-api/extension-api-services/applications-nav-service.md)
{% endcontent-ref %}

### **UI Service**

Use the `ui` service to extend various parts of the Symphony client user interface. For example, add buttons on 1 to 1 chats and chatroom modules or add links to the **#**hashtag and $cashtag hovercards:

{% content-ref url="/pages/-MJPWunLWVovXwbEuUf2" %}
[UI Service](/ext-apps/overview-of-extension-api/extension-api-services/ui-service.md)
{% endcontent-ref %}

### **Share Service**

Use the `share` service to allow users to share content from your application into Symphony conversations**:**

{% content-ref url="/pages/-MJPWunI4FaBeCP9mHE2" %}
[Share Service](/ext-apps/overview-of-extension-api/extension-api-services/share-service.md)
{% endcontent-ref %}

### **Entity Service**

Use the `entity` service to allow your app to render a Structured Object within a within a message sent by the REST API:

{% content-ref url="/pages/-MJPWunF27H8sxZbRl9w" %}
[Entity Service](/ext-apps/overview-of-extension-api/extension-api-services/entity-service.md)
{% endcontent-ref %}

### **Commerce Service**

Apps can offer premium functionality through licensed subscriptions. Use the `commerce` service to identify the products (premium versions) to which a user is subscribed**:**

{% content-ref url="/pages/-MJPWunJmJmwodqUG8qQ" %}
[Commerce Service](/ext-apps/overview-of-extension-api/extension-api-services/commerce-service.md)
{% endcontent-ref %}

### **Dialogs Service**

Use the `dialogs` service to create modal windows (e.g. to open a modal window from a button registered at a room level)**:**

{% content-ref url="/pages/-MJPWunKIQ\_7\_fRQ9foz" %}
[Dialogs Service](/ext-apps/overview-of-extension-api/extension-api-services/dialogs-service.md)
{% endcontent-ref %}

## Service Interface

Both the Client Extensions API services and your application services use the same interface. Continue here to learn how to implement the Service interface methods:

{% content-ref url="/pages/-MJPWunCAIc6Z4cn\_JTa" %}
[Service Interface](/ext-apps/overview-of-extension-api/extension-api-services/service-interface.md)
{% endcontent-ref %}


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