You can send messages to devices that are subscribed to a particular topic using
the Admin SDK or the FCM v1 HTTP API.

## Prerequisites

- Set up the necessary environment for sending messages using your chosen
  method. See [Set Up Your Server
  Environment](https://firebase.google.com/docs/cloud-messaging/server-environment).

- Client apps must be subscribed to the topic. See [Manage Topic
  Subscriptions](https://firebase.google.com/docs/cloud-messaging/manage-topic-subscriptions).

## Sending to a Topic

You can send messages to a topic using either the Firebase Admin SDK or the FCM
HTTP v1 API.

> [!IMPORTANT]
> **Important:** Once an FCM fanout request is received, it's fully committed and cannot be canceled through the FCM APIs, console, or Firebase console support.

### Using the Admin SDK

You can use the Admin SDK to send topic messages from your server. To learn more
about setting up the Admin SDK, see [Send Messages using the Admin
SDK](https://firebase.google.com/docs/cloud-messaging/send/admin-sdk).

### Node.js

```javascript
// The topic name can be optionally prefixed with "/topics/".
const topic = 'highScores';

const message = {
  data: {
    score: '850',
    time: '2:45'
  },
  topic: topic
};

// Send a message to devices subscribed to the provided topic.
getMessaging().send(message)
  .then((response) => {
    // Response is a message ID string.
    console.log('Successfully sent message:', response);
  })
  .catch((error) => {
    console.log('Error sending message:', error);
  });
```

### Java

```java
// The topic name can be optionally prefixed with "/topics/".
String topic = "highScores";

// See documentation on defining a message payload.
Message message = Message.builder()
    .putData("score", "850")
    .putData("time", "2:45")
    .setTopic(topic)
    .build();

// Send a message to the devices subscribed to the provided topic.
String response = FirebaseMessaging.getInstance().sendAsync(message).get();
// Response is a message ID string.
System.out.println("Successfully sent message: " + response);
```

### Python

```python
# The topic name can be optionally prefixed with "/topics/".
topic = 'highScores'

# See documentation on defining a message payload.
message = messaging.Message(
    data={
        'score': '850',
        'time': '2:45',
    },
    topic=topic,
)

# Send a message to the devices subscribed to the provided topic.
response = messaging.send(message)
# Response is a message ID string.
print('Successfully sent message:', response)
```

### Go

```go
// The topic name can be optionally prefixed with "/topics/".
topic := "highScores"

// See documentation on defining a message payload.
message := &messaging.Message{
	Data: map[string]string{
		"score": "850",
		"time":  "2:45",
	},
	Topic: topic,
}

// Send a message to the devices subscribed to the provided topic.
response, err := client.Send(ctx, message)
if err != nil {
	log.Fatalln(err)
}
// Response is a message ID string.
fmt.Println("Successfully sent message:", response)
```

### C#

```c#
// The topic name can be optionally prefixed with "/topics/".
var topic = "highScores";

// See documentation on defining a message payload.
var message = new Message()
{
    Data = new Dictionary<string, string>()
    {
        { "score", "850" },
        { "time", "2:45" },
    },
    Topic = topic,
};

// Send a message to the devices subscribed to the provided topic.
string response = await FirebaseMessaging.DefaultInstance.SendAsync(message);
// Response is a message ID string.
Console.WriteLine("Successfully sent message: " + response);
```

### Using the HTTP v1 API

To send topic messages using the HTTP v1 API, construct a JSON POST request. To
learn more about using the HTTP v1 API, see [Send a Message via FCM v1
API](https://firebase.google.com/docs/cloud-messaging/send/v1-api).

### REST

```restructuredtext
POST https://fcm.googleapis.com/v1/projects/myproject-b5ae1/messages:send HTTP/1.1

Content-Type: application/json
Authorization: Bearer ya29.ElqKBGN2Ri_Uz...HnS_uNreA
{
  "message":{
    "topic" : "foo-bar",
    "notification" : {
      "body" : "This is a Firebase Cloud Messaging Topic Message!",
      "title" : "FCM Message"
      }
   }
}
```

cURL command:

```restructuredtext
curl -X POST -H "Authorization: Bearer ya29.ElqKBGN2Ri_Uz...HnS_uNreA" -H "Content-Type: application/json" -d '{
  "message": {
    "topic" : "foo-bar",
    "notification": {
      "body": "This is a Firebase Cloud Messaging Topic Message!",
      "title": "FCM Message"
    }
  }
}' https://fcm.googleapis.com/v1/projects/myproject-b5ae1/messages:send HTTP/1.1
```

## Sending to Topic Conditions

To send a message to a *combination* of topics, specify a *condition* , which is
a boolean expression that specifies the target topics. For example, the
following condition will send messages to devices that are subscribed to
`TopicA` and either `TopicB` or `TopicC`:

`"'TopicA' in topics && ('TopicB' in topics || 'TopicC' in topics)"`

FCM first evaluates any conditions in parentheses, and then evaluates
the expression from left to right. You can include up to five topics in your
conditional expression.

> [!TIP]
> **Tip:** If you often send messages to a specific combination of topics, consider creating a new topic for that user group. This is more efficient than using topic conditions. For example, instead of sending messages to subscribers of `TopicA` and `TopicB` using the condition `"'TopicA' in topics && 'TopicB' in topics"`, create a new topic `TopicAandB`, subscribe the relevant users to it, and send messages directly to `TopicAandB`.

### Using the Admin SDK

### Node.js

```javascript
// Define a condition which will send to devices which are subscribed
// to either the Google stock or the tech industry topics.
const condition = '\'stock-GOOG\' in topics || \'industry-tech\' in topics';

// See documentation on defining a message payload.
const message = {
  notification: {
    title: '$FooCorp up 1.43% on the day',
    body: '$FooCorp gained 11.80 points to close at 835.67, up 1.43% on the day.'
  },
  condition: condition
};

// Send a message to devices subscribed to the combination of topics
// specified by the provided condition.
getMessaging().send(message)
  .then((response) => {
    // Response is a message ID string.
    console.log('Successfully sent message:', response);
  })
  .catch((error) => {
    console.log('Error sending message:', error);
  });
```

### Java

```java
// Define a condition which will send to devices which are subscribed
// to either the Google stock or the tech industry topics.
String condition = "'stock-GOOG' in topics || 'industry-tech' in topics";

// See documentation on defining a message payload.
Message message = Message.builder()
    .setNotification(Notification.builder()
            .setTitle("$GOOG up 1.43% on the day")
            .setBody("$GOOG gained 11.80 points to close at 835.67, up 1.43% on the day.")
            .build())
    .setCondition(condition)
    .build();

// Send a message to devices subscribed to the combination of topics
// specified by the provided condition.
String response = FirebaseMessaging.getInstance().sendAsync(message).get();
// Response is a message ID string.
System.out.println("Successfully sent message: " + response);
```

### Python

```python
# Define a condition which will send to devices which are subscribed
# to either the Google stock or the tech industry topics.
condition = "'stock-GOOG' in topics || 'industry-tech' in topics"

# See documentation on defining a message payload.
message = messaging.Message(
    notification=messaging.Notification(
        title='$GOOG up 1.43% on the day',
        body='$GOOG gained 11.80 points to close at 835.67, up 1.43% on the day.',
    ),
    condition=condition,
)

# Send a message to devices subscribed to the combination of topics
# specified by the provided condition.
response = messaging.send(message)
# Response is a message ID string.
print('Successfully sent message:', response)
```

### Go

```go
// Define a condition which will send to devices which are subscribed
// to either the Google stock or the tech industry topics.
condition := "'stock-GOOG' in topics || 'industry-tech' in topics"

// See documentation on defining a message payload.
message := &messaging.Message{
	Data: map[string]string{
		"score": "850",
		"time":  "2:45",
	},
	Condition: condition,
}

// Send a message to devices subscribed to the combination of topics
// specified by the provided condition.
response, err := client.Send(ctx, message)
if err != nil {
	log.Fatalln(err)
}
// Response is a message ID string.
fmt.Println("Successfully sent message:", response)
```

### C#

```c#
// Define a condition which will send to devices which are subscribed
// to either the Google stock or the tech industry topics.
var condition = "'stock-GOOG' in topics || 'industry-tech' in topics";

// See documentation on defining a message payload.
var message = new Message()
{
    Notification = new Notification()
    {
        Title = "$GOOG up 1.43% on the day",
        Body = "$GOOG gained 11.80 points to close at 835.67, up 1.43% on the day.",
    },
    Condition = condition,
};

// Send a message to devices subscribed to the combination of topics
// specified by the provided condition.
string response = await FirebaseMessaging.DefaultInstance.SendAsync(message);
// Response is a message ID string.
Console.WriteLine("Successfully sent message: " + response);
```

### Using the HTTP v1 API

### REST

```restructuredtext
POST https://fcm.googleapis.com/v1/projects/myproject-b5ae1/messages:send HTTP/1.1

Content-Type: application/json
Authorization: Bearer ya29.ElqKBGN2Ri_Uz...HnS_uNreA
{
   "message":{
    "condition": "'dogs' in topics || 'cats' in topics",
    "notification" : {
      "body" : "This is a Firebase Cloud Messaging Topic Message!",
      "title" : "FCM Message",
    }
  }
}
```

cURL command:

```restructuredtext
curl -X POST -H "Authorization: Bearer ya29.ElqKBGN2Ri_Uz...HnS_uNreA" -H "Content-Type: application/json" -d '{
  "notification": {
    "title": "FCM Message",
    "body": "This is a Firebase Cloud Messaging Topic Message!",
  },
  "condition": "'dogs' in topics || 'cats' in topics"
}' https://fcm.googleapis.com/v1/projects/myproject-b5ae1/messages:send HTTP/1.1
```

## Handling Topic Messages in the App

Once you send a message to a topic, FCM delivers it to all subscribed
client app instances.

To learn how to receive and process messages in your Android, iOS, or Web app,
see [Receive
Messages](https://firebase.google.com/docs/cloud-messaging/receive-messages).