Reactions

Stream Chat supports message reactions such as likes, hearts, and custom reaction types. Users can react to messages, and reactions can include custom data and scores for cumulative reactions.

Sending a Reaction

Add a reaction to a message using the sendReaction method. Each user can have one reaction of each type per message.

var resp = await chat.SendReactionAsync(messageId,
    new SendReactionRequest
    {
        Reaction = new ReactionRequest
        {
            Type = "love",
            UserID = userId
        }
    });

Reaction Parameters

Name	Type	Description	Default	Optional
message_id	string	ID of the message to react to
type	string	Reaction type. Each user can have one reaction of each type per message.
score	integer	Score for cumulative reactions	1	✓
user_id	string	User ID (required for server-side calls)		✓
enforce_unique	boolean	If true, replaces all existing reactions from this user with the new one	false	✓
skip_push	boolean	If true, do not send a push notification	false	✓
emoji_code	string	Unicode emoji for push notification display		✓
custom data	object	Custom fields for the reaction		✓

Warning:

Custom data for reactions is limited to 1KB.

Removing a Reaction

Remove a reaction by specifying the message ID and reaction type.

await chat.DeleteReactionAsync(messageId, "love",
    new { user_id = userId });

Field	Type	Description
reaction_counts	object	Count of reactions per type. Example: `{"love": 3, "fire": 2}`
reaction_scores	object	Sum of scores per type. Equals counts for standard reactions; differs for cumulative reactions.
reaction_groups	object	Detailed statistics per type including count, sum_scores, first_reaction_at, last_reaction_at
latest_reactions	array	The 10 most recent reactions with type, user_id, and created_at
own_reactions	array	The current user's reactions on this message

Use reaction_groups instead of reaction_counts for if you're building a custom implementation. The reaction_groups field provides additional metadata including timestamps and is the recommended approach.

To retrieve more than 10 reactions, use pagination.

Paginating Reactions

Retrieve reactions with pagination using limit and offset parameters.

Parameter	Maximum Value
limit	300
offset	1000

// Get the first 10 reactions
var resp = await chat.GetReactionsAsync(messageId, new { limit = 10 });

// Get reactions 11-13
var nextResp = await chat.GetReactionsAsync(messageId, new { limit = 3, offset = 10 });

Querying Reactions

Filter reactions by type or user on a specific message. This endpoint requires the user to have read permission on the channel when called client-side.

JavaScript

// Query reactions by type
await client.queryReactions(message.id, { type: "like" });

// Query reactions by user
await client.queryReactions(message.id, { user_id: userId });

// Paginate results
const firstPage = await client.queryReactions(message.id, {});
const secondPage = await client.queryReactions(
  message.id,
  {},
  {},
  { limit: 5, next: firstPage.next },
);

Cumulative Reactions

Cumulative reactions allow users to react multiple times to the same message, with the total score tracked. This is useful for features like Medium's "clap" functionality.

Set a score value when sending the reaction. The API returns:

sum_scores: Total score across all users
Individual user scores

var resp = await chat.SendReactionAsync(messageId,
    new SendReactionRequest
    {
        Reaction = new ReactionRequest
        {
            Type = "clap",
            UserID = userId,
            Score = 5
        }
    });