> ## Documentation Index
> Fetch the complete documentation index at: https://www.cometchat.com/docs/llms.txt
> Use this file to discover all available pages before exploring further.

# Constraints And Limits

> Constraints And Limits — CometChat documentation.

Use this page to confirm supported SDK/UI Kit versions, platform/browser coverage, hard limits, and known notification caveats before you ship.

## What you need (SDKs/UI Kits)

To implement Notifications, use the minimum versions below (UI Kits already bundle the matching Chat and Call SDKs):

* **UI Kits**: v4+ (Flutter Calls UI Kit v4.3.0+)
* **Calls SDK**: all versions (Flutter Calls SDK v4.0.9+)
* **Chat SDK**: iOS v4.0.51+, Android v4.0.9+, Flutter v4.0.15+, React Native v4.0.10+, JavaScript v4.0.8+, Ionic (Cordova) v4.0.8+ (Deprecated - use JavaScript SDK)
* Chat Widgets are not compatible with push notifications.

<Info>
  It is possible to use Notification features without using UI Kits with an entirely SDK dependent solution with the above-mentioned SDK versions.
</Info>

## Supported web browsers

* Chrome 50+
* Firefox 44+
* Edge 17+
* Opera 42+

## Supported platforms

* iOS v11+
* Android v21+
* Flutter v2.17+
* React Native v0.73 and earlier
* React v18 and earlier
* Angular v17 and earlier
* Vue v3 and earlier
* Capacitor v6 and earlier

## Limits (delivery and content)

| Entity / Parameter                                   | Limit                                                                                               |
| ---------------------------------------------------- | --------------------------------------------------------------------------------------------------- |
| Maximum group size supported for Push Notifications  | 1000 members or less                                                                                |
| Maximum group size supported for Email Notifications | 30 members or less                                                                                  |
| Maximum group size supported for SMS Notifications   | 30 members or less                                                                                  |
| Maximum Push tokens by an auth token                 | 1                                                                                                   |
| Maximum SMS length                                   | 160 characters. (If a message exceeds this limit, the remaining content will go as another message) |
| Minimum interval between two emails (in minutes)     | 1 minute.                                                                                           |
| Minimum interval between two SMS (in minutes)        | 1 minute.                                                                                           |

## Platform-specific limitations

* **iOS**: Calling notifications work only with APNs (VoIP). FCM calling notifications are not supported (native iOS, React Native iOS, Flutter iOS).
* **Android**: FCM push works on devices with Google Mobile Services; it does not work on Huawei devices.
* **Flutter (Android) with FCM**: In the foreground, edited/deleted message notifications may still show the original text.
* **Browser notifications** are not supported on mobile devices.
* **Calling Notifications** are not supported in web browsers.