> ## Documentation Index > Fetch the complete documentation index at: https://cometchat-22654f5b-feature-react-native-sdk-quotedmessage-a.mintlify.site/llms.txt > Use this file to discover all available pages before exploring further. # Constraints, Rate Limits And Errors ## Constraints, Rate limits and Errors: ### Properties and Constraints: #### **API Keys: Properties and Constraints** | **Item** | **Property or Constraint** | **Notes** | | ---------------------------------------------------------- | ----------------------------------- | ------------------------------------------------------------------------------- | | API Keys | 100 characters (UTF8mb4 Characters) | This covers all the languages and even emojis. (One emoji uses two characters). | | Maximum number of APIs keys that can be created for an app | 25 | | #### **Users and Groups: Properties and Constraints** | **Item** | **Property or Constraint** | **Notes** | | ------------------------------------------------------ | ------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------ | ------------------------------------------------------------------------------------------------------------------------------ | | Character limits for UIDs and GUIDs | 100 characters | | | Maximum users in a group (v3) | 100000 | | | Maximum groups a user can be a part of | 2000 | | | Maximum number of friends for a user | 1000 | | | Maximum tokens for a user | No limits | | | Maximum Number of Bot users that can be created | 25 | | | Maximum number of groups | No limits | | | Maximum number of unread messages per user | No limits | | | Maximum number of users that can be created for an app | No limits | | | User and Group ID | 100 characters, alpha-dash (a-z, 0-9 with -and \_) without spaces . | CometChat forces the UID to all lowercase. | | User and Group name | 100 characters, UTF8mb4 set | This covers all the languages and even emojis. | | User and Group avatar | Must be a URL, limit of 3000 characters | CometChat doesn't save the image on its servers.. There is no limit on the image resolution. It depends on the implementation. | | User profile | Must be a URL, limit of 3000 characters | Same as above | | User and Group metadata | The API limit for the POST request length is 10 KB. Hence, the user's metadata information must fit in the same limit and must not exceed 5 KB. | | | User and Group tag | A user can have up to 25 tags with 100 characters per tag. The tags can be in any language. The character set must be UTF8mb4 | | | Group password | String up to 100 characters | | | Group description | 255 characters, UTF8mb4 set | | | Maximum active presence subscriptions | The presence subscription will be active until 1000 users are online for a single app. if more than 1000 users go online, the presence notification starting from the 1001st user will not be sent to other users. | Note, this is the higher limit applicable across subscription for friends, users with certain roles and all users | | Typing indicators for groups | Typing indicator will be sent for a group of up to 1000 online users. | | | Unread message counts for groups | For a group with more than 300 members, the conversations and unread message counts are not updated. | | | Delivery and read receipts for groups | Delivery and read receipts will be sent for a group of up to 300 online users. | | #### **Roles: Properties and Constraints** | **Item** | **Property or Constraint** | **Notes** | | ------------------------------------------- | ----------------------------------------------------------------- | ---------------------------------------------- | | Maximum number of Roles that can be created | Maximum 25 | | | Role UID | 100 characters, alpha-dash (a-z, 0-9 with -and \_) without spaces | CometChat forces the UID to lowercase. | | Role name | 100 characters, UTF8mb4 | This covers all the languages and even emojis. | | Role description | 255 characters, UTF8mb4 set, any language. | | | Metadata | No limit | | #### **Messages: Properties and Constraints** | Item | Property or Constraint | Notes | | ----------------------------- | -------------------------------------------------------------------------------------------------------------------------------------------------------- | ------------------------------------------------------------------------------------------------------------------------- | | File size | Maximum file size per message: 100 MB | Applies to the uploaded file associated with the message. | | Message Data | Arbitrary JSON (UTF-8/utf8mb4), up to 10 KB for the data object; keys with special meaning to CometChat: `text`, `attachments`, `customData`, `metadata` | Attachment properties (for example, URL and size) can be included here; the actual file limit is defined under File size. | | Groups → Unread message count | For groups with more than 300 members, conversation and unread message counts are not updated | | | Groups → Message receipts | Delivery and read receipts are sent for groups with up to 300 members | | | Tags | Up to 25 tags per message; 100 characters per tag (UTF-8/utf8mb4) | Tags can be in any language. | | User mentions | Up to 10 distinct users can be mentioned in a message | Format: `<@uid:{uid of the user}>` (example: `<@uid:cometchat-uid-1>`). | | Reactions | Maximum 25 distinct reactions per message; reaction text up to 45 characters (UTF-8/utf8mb4) | Character counts are by Unicode code points. Emoji are supported and may use multiple code points. | #### **Calling: Properties and Constraints** | **Item** | **Property or Constraint** | **Notes** | | ---------------------------------- | ------------------------------ | --------------------------------------------------------------------------------- | | Maximum users in a call | 50 | | | Default frame rate for video calls | 30 FPS | | | Resolution for video calls | Maximum - 720p, Minimum - 180p | This depends on the layout selected and the bandwidth available at the user's end | | Media encryption used | SRTP | | | Audio codec used | OPUS | | | Video codec used | H.264 | | ### Rate Limits: **Groups** 1. `GUID` must be less than 100 characters & must be alpha-numeric-dash. 2. Groups (with all features) can be as large as 300 members. 3. Groups (without delivery & read receipts & typing indicators) can be as large as 50,000 members and can have up to 10,000 concurrent members. **Users** 1. `UID` must be less than 100 characters & must be alpha-numeric-dash. 2. A user can have up to 500 friends. 3. Presence subscription for all users is limited to 1000 users. **Messages** 1. Messages must be less than 65Kb. **Voice & Video Calling** 1. Up to 4 users can participate in a single voice or video call. **API** 1. API calls for core operations are rate limited to 10,000 requests per min. Core operations include user connection, create/delete user, create/join group cumulatively. 2. API calls for standard operations are rate limited to 20,000 requests per min. Standard operations include all other operations cumulatively. **Bots** 1. `UID` must be less than 50 characters. ### Webhooks: | **Item** | **Property or Constraint** | **Notes** | | ------------------------------- | --------------------------------------------------------- | --------- | | Webhook URL | Valid URL, maximum 255 characters | | | Webhook ID | 50 characters, UTF8mb4 set, alphanumeric (without spaces) | | | Webhook authentication username | 50 characters, alphanumeric (without spaces) | | | Webhook authentication password | 100 characters, alphanumeric (without spaces) | | ### Errors: