# Trigger

A trigger is the first step in every Automation. It defines which event will start the Automation when received.

When your application sends an event to Resend, every active Automation with a matching trigger will execute its workflow for that contact.

## How it works

:::::tabs
:::tab{title="Using the dashboard"}
The trigger is the first node in the editor.

![Add Trigger to Automation](../img/site-assets/mintcdn.com/resend/ePnINhGLisYSJsWT/images/automations-trigger-5etbgx.png)

Choose an existing [custom event](/guides/learn-dashboard-automations-custom-events) or type a new event name.

![Add Custom Event](../img/site-assets/mintcdn.com/resend/ePnINhGLisYSJsWT/images/automations-custom-event-npzwp1.png)
:::

::::tab{title="Using the API"}
When creating an Automation via the API, the trigger is defined as the first item in the `steps` array with `type: 'trigger'`.

:::code-group
```ts Node.js {8-12} theme={"theme":{"light":"github-light","dark":"vesper"}}
import { Resend } from 'resend';

const resend = new Resend('re_xxxxxxxxx');

const { data, error } = await resend.automations.create({
  name: 'Welcome series',
  steps: [
    {
      key: 'start',
      type: 'trigger',
      config: { eventName: 'user.created' },
    },
  ],
  connections: [],
});
```

```php PHP {6-10} theme={"theme":{"light":"github-light","dark":"vesper"}}
$resend = Resend::client('re_xxxxxxxxx');

$resend->automations->create([
  'name' => 'Welcome series',
  'steps' => [
    [
      'key' => 'start',
      'type' => 'trigger',
      'config' => ['event_name' => 'user.created'],
    ],
  ],
  'connections' => [],
]);
```

```python Python {8-12} theme={"theme":{"light":"github-light","dark":"vesper"}}
import resend

resend.api_key = "re_xxxxxxxxx"

params: resend.Automations.CreateParams = {
  "name": "Welcome series",
  "steps": [
    {
      "key": "start",
      "type": "trigger",
      "config": {"event_name": "user.created"},
    },
  ],
  "connections": [],
}

resend.Automations.create(params)
```

```ruby Ruby {8-12} theme={"theme":{"light":"github-light","dark":"vesper"}}
require "resend"

Resend.api_key = "re_xxxxxxxxx"

params = {
  name: "Welcome series",
  steps: [
    {
      key: "start",
      type: "trigger",
      config: { event_name: "user.created" },
    },
  ],
  connections: [],
}

Resend::Automations.create(params)
```

```go Go {11-17} theme={"theme":{"light":"github-light","dark":"vesper"}}
package main

import "github.com/resend/resend-go/v4"

func main() {
	client := resend.NewClient("re_xxxxxxxxx")

	params := &resend.CreateAutomationRequest{
		Name: "Welcome series",
		Steps: []resend.AutomationStep{
			{
				Key:  "start",
				Type: resend.AutomationStepTypeTrigger,
				Config: map[string]any{
					"event_name": "user.created",
				},
			},
		},
		Connections: []resend.AutomationConnection{},
	}

	client.Automations.Create(params)
}
```

```rust Rust {11-16} theme={"theme":{"light":"github-light","dark":"vesper"}}
use resend_rs::{
  types::{AutomationStatus, CreateAutomationOptions, Step, TriggerStepConfig},
  Resend, Result,
};

#[tokio::main]
async fn main() -> Result<()> {
  let resend = Resend::new("re_xxxxxxxxx");

  let opts = CreateAutomationOptions {
    name: "Welcome series".to_owned(),
    steps: vec![Step::Trigger {
      key: "start".to_owned(),
      config: TriggerStepConfig {
        event_name: "user.created".to_owned(),
      },
    }],
    connections: vec![],
    status: AutomationStatus::Disabled,
  };
  let _automation = resend.automations.create(opts).await?;

  Ok(())
}
```

```java Java {13-17} theme={"theme":{"light":"github-light","dark":"vesper"}}
import com.resend.*;
import com.resend.core.exception.ResendException;
import com.resend.services.automations.model.AutomationStep;
import com.resend.services.automations.model.CreateAutomationOptions;
import com.resend.services.automations.model.CreateAutomationResponseSuccess;

public class Main {
    public static void main(String[] args) throws ResendException {
        Resend resend = new Resend("re_xxxxxxxxx");

        CreateAutomationOptions options = CreateAutomationOptions.builder()
                .name("Welcome series")
                .steps(
                    AutomationStep.trigger("start")
                        .eventName("user.created")
                        .build()
                )
                .build();

        CreateAutomationResponseSuccess data = resend.automations().create(options);
    }
}
```

```csharp .NET {6,13} theme={"theme":{"light":"github-light","dark":"vesper"}}
using Resend;
using System.Text.Json;

IResend resend = ResendClient.Create( "re_xxxxxxxxx" );

var startConfig = JsonSerializer.SerializeToElement( new { event_name = "user.created" } );

var resp = await resend.AutomationCreateAsync( new AutomationCreateData()
{
    Name = "Welcome series",
    Steps = new List<AutomationStepData>
    {
        new AutomationStepData { Ref = "start", Type = "trigger", Config = startConfig },
    },
    Connections = new List<AutomationEdge>(),
} );
```

```bash cURL {6-10} theme={"theme":{"light":"github-light","dark":"vesper"}}
curl -X POST 'https://api.resend.com/automations' \
     -H 'Authorization: Bearer re_xxxxxxxxx' \
     -H 'Content-Type: application/json' \
     -d '{
  "name": "Welcome series",
  "steps": [{
    "key": "start",
    "type": "trigger",
    "config": { "event_name": "user.created" }
  }],
  "connections": []
}'
```

```bash CLI theme={"theme":{"light":"github-light","dark":"vesper"}}
resend automations create --name "Welcome series" --file ./automation.json
```
:::
::::
:::::

:::callout{intent="warning"}
Event names cannot start with the `resend:` prefix, which is reserved for
system events.
:::

## Identifying contacts

When sending an event to trigger an Automation, you must identify the contact using either a `contact_id` or an `email` address.

:::::tabs
::::tab{title="Using contact ID"}
Use a contact ID when you already have the contact stored in your [Audience](/guides/learn-dashboard-audiences-introduction):

:::code-group
```ts Node.js {7} theme={"theme":{"light":"github-light","dark":"vesper"}}
import { Resend } from 'resend';

const resend = new Resend('re_xxxxxxxxx');

const { data, error } = await resend.events.send({
  event: 'user.created',
  contactId: '26e2b838-bf6d-4515-b6a7-17525b12b05a',
  payload: {
    plan: 'pro',
  },
});
```

```php PHP {5} theme={"theme":{"light":"github-light","dark":"vesper"}}
$resend = Resend::client('re_xxxxxxxxx');

$resend->events->send([
  'event' => 'user.created',
  'contact_id' => '26e2b838-bf6d-4515-b6a7-17525b12b05a',
  'payload' => ['plan' => 'pro'],
]);
```

```python Python {7} theme={"theme":{"light":"github-light","dark":"vesper"}}
import resend

resend.api_key = "re_xxxxxxxxx"

params: resend.Events.SendParams = {
  "event": "user.created",
  "contact_id": "26e2b838-bf6d-4515-b6a7-17525b12b05a",
  "payload": {"plan": "pro"},
}

resend.Events.send(params)
```

```ruby Ruby {7} theme={"theme":{"light":"github-light","dark":"vesper"}}
require "resend"

Resend.api_key = "re_xxxxxxxxx"

params = {
  event: "user.created",
  contact_id: "26e2b838-bf6d-4515-b6a7-17525b12b05a",
  payload: { plan: "pro" },
}

Resend::Events.send(params)
```

```go Go {10} theme={"theme":{"light":"github-light","dark":"vesper"}}
package main

import "github.com/resend/resend-go/v4"

func main() {
	client := resend.NewClient("re_xxxxxxxxx")

	client.Events.Send(&resend.SendEventRequest{
		Event:     "user.created",
		ContactId: "26e2b838-bf6d-4515-b6a7-17525b12b05a",
		Payload: map[string]any{
			"plan": "pro",
		},
	})
}
```

```rust Rust {15-17} theme={"theme":{"light":"github-light","dark":"vesper"}}
use resend_rs::{
  json,
  types::{ContactIdOrEmail, SendEventOptions},
  Resend, Result,
};

#[tokio::main]
async fn main() -> Result<()> {
  let resend = Resend::new("re_xxxxxxxxx");

  let _event = resend
    .events
    .send(SendEventOptions {
      event: "user.created".to_owned(),
      contact_id_or_email: ContactIdOrEmail::ContactId(
        "26e2b838-bf6d-4515-b6a7-17525b12b05a".to_owned(),
      ),
      payload: json!({ "plan": "pro" }),
    })
    .await?;

  Ok(())
}
```

```java Java {10} theme={"theme":{"light":"github-light","dark":"vesper"}}
import com.resend.*;
import com.resend.core.exception.ResendException;
import com.resend.services.events.model.*;

public class Main {
    public static void main(String[] args) throws ResendException {
        Resend resend = new Resend("re_xxxxxxxxx");

        SendEventOptions params = SendEventOptions.builder()
                .event("user.created")
                .contactId("26e2b838-bf6d-4515-b6a7-17525b12b05a")
                .addPayload("plan", "pro")
                .build();

        SendEventResponseSuccess data = resend.events().send(params);
    }
}
```

```csharp .NET {11} theme={"theme":{"light":"github-light","dark":"vesper"}}
using Resend;
using System.Text.Json;

IResend resend = ResendClient.Create( "re_xxxxxxxxx" );

var payload = JsonSerializer.SerializeToElement( new { plan = "pro" } );

var resp = await resend.EventSendAsync( new EventSendData()
{
    Event = "user.created",
    ContactId = new Guid( "26e2b838-bf6d-4515-b6a7-17525b12b05a" ),
    Payload = payload,
} );
```

```bash cURL {6} theme={"theme":{"light":"github-light","dark":"vesper"}}
curl -X POST 'https://api.resend.com/events/send' \
     -H 'Authorization: Bearer re_xxxxxxxxx' \
     -H 'Content-Type: application/json' \
     -d '{
  "event": "user.created",
  "contact_id": "26e2b838-bf6d-4515-b6a7-17525b12b05a",
  "payload": {
    "plan": "pro"
  }
}'
```

```bash CLI theme={"theme":{"light":"github-light","dark":"vesper"}}
resend events send \
  --event user.created \
  --contact-id 26e2b838-bf6d-4515-b6a7-17525b12b05a \
  --payload '{"plan":"pro"}'
```
:::
::::

::::tab{title="Using email address"}
Use an email address to trigger the Automation. If no contact with the provided email exists in your Audience, Resend will automatically create one when the run starts.

:::code-group
```ts Node.js {7} theme={"theme":{"light":"github-light","dark":"vesper"}}
import { Resend } from 'resend';

const resend = new Resend('re_xxxxxxxxx');

const { data, error } = await resend.events.send({
  event: 'user.created',
  email: 'user@example.com',
  payload: {
    plan: 'pro',
  },
});
```

```php PHP {5} theme={"theme":{"light":"github-light","dark":"vesper"}}
$resend = Resend::client('re_xxxxxxxxx');

$resend->events->send([
  'event' => 'user.created',
  'email' => 'user@example.com',
  'payload' => ['plan' => 'pro'],
]);
```

```python Python {7} theme={"theme":{"light":"github-light","dark":"vesper"}}
import resend

resend.api_key = "re_xxxxxxxxx"

params: resend.Events.SendParams = {
  "event": "user.created",
  "email": "user@example.com",
  "payload": {"plan": "pro"},
}

resend.Events.send(params)
```

```ruby Ruby {7} theme={"theme":{"light":"github-light","dark":"vesper"}}
require "resend"

Resend.api_key = "re_xxxxxxxxx"

params = {
  event: "user.created",
  email: "user@example.com",
  payload: { plan: "pro" },
}

Resend::Events.send(params)
```

```go Go {10} theme={"theme":{"light":"github-light","dark":"vesper"}}
package main

import "github.com/resend/resend-go/v4"

func main() {
	client := resend.NewClient("re_xxxxxxxxx")

	client.Events.Send(&resend.SendEventRequest{
		Event: "user.created",
		Email: "user@example.com",
		Payload: map[string]any{
			"plan": "pro",
		},
	})
}
```

```rust Rust {15} theme={"theme":{"light":"github-light","dark":"vesper"}}
use resend_rs::{
  json,
  types::{ContactIdOrEmail, SendEventOptions},
  Resend, Result,
};

#[tokio::main]
async fn main() -> Result<()> {
  let resend = Resend::new("re_xxxxxxxxx");

  let _event = resend
    .events
    .send(SendEventOptions {
      event: "user.created".to_owned(),
      contact_id_or_email: ContactIdOrEmail::Email("user@example.com".to_owned()),
      payload: json!({ "plan": "pro" }),
    })
    .await?;

  Ok(())
}
```

```java Java {10} theme={"theme":{"light":"github-light","dark":"vesper"}}
import com.resend.*;
import com.resend.core.exception.ResendException;
import com.resend.services.events.model.*;

public class Main {
    public static void main(String[] args) throws ResendException {
        Resend resend = new Resend("re_xxxxxxxxx");

        SendEventOptions params = SendEventOptions.builder()
                .event("user.created")
                .email("user@example.com")
                .addPayload("plan", "pro")
                .build();

        SendEventResponseSuccess data = resend.events().send(params);
    }
}
```

```csharp .NET {11} theme={"theme":{"light":"github-light","dark":"vesper"}}
using Resend;
using System.Text.Json;

IResend resend = ResendClient.Create( "re_xxxxxxxxx" );

var payload = JsonSerializer.SerializeToElement( new { plan = "pro" } );

var resp = await resend.EventSendAsync( new EventSendData()
{
    Event = "user.created",
    Email = "user@example.com",
    Payload = payload,
} );
```

```bash cURL {6} theme={"theme":{"light":"github-light","dark":"vesper"}}
curl -X POST 'https://api.resend.com/events/send' \
     -H 'Authorization: Bearer re_xxxxxxxxx' \
     -H 'Content-Type: application/json' \
     -d '{
  "event": "user.created",
  "email": "user@example.com",
  "payload": {
    "plan": "pro"
  }
}'
```

```bash CLI theme={"theme":{"light":"github-light","dark":"vesper"}}
resend events send \
  --event user.created \
  --email user@example.com \
  --payload '{"plan":"pro"}'
```
:::
::::
:::::

## Event payload

You can include a `payload` object with your event to pass data into the Automation. This data becomes available as variables in subsequent steps in the Automation using the `event.*` namespace.

:::code-group
```ts Node.js {8-12} theme={"theme":{"light":"github-light","dark":"vesper"}}
import { Resend } from 'resend';

const resend = new Resend('re_xxxxxxxxx');

const { data, error } = await resend.events.send({
  event: 'payment.failed',
  contactId: 'e169aa45-1ecf-4183-9955-b1499d5701d3',
  payload: {
    amount: 49.99,
    currency: 'USD',
    retryDate: '2026-11-01',
  },
});
```

```php PHP {6-10} theme={"theme":{"light":"github-light","dark":"vesper"}}
$resend = Resend::client('re_xxxxxxxxx');

$resend->events->send([
  'event' => 'payment.failed',
  'contact_id' => 'e169aa45-1ecf-4183-9955-b1499d5701d3',
  'payload' => [
    'amount' => 49.99,
    'currency' => 'USD',
    'retryDate' => '2026-11-01',
  ],
]);
```

```python Python {8-12} theme={"theme":{"light":"github-light","dark":"vesper"}}
import resend

resend.api_key = "re_xxxxxxxxx"

params: resend.Events.SendParams = {
  "event": "payment.failed",
  "contact_id": "e169aa45-1ecf-4183-9955-b1499d5701d3",
  "payload": {
    "amount": 49.99,
    "currency": "USD",
    "retryDate": "2026-11-01",
  },
}

resend.Events.send(params)
```

```ruby Ruby {8-12} theme={"theme":{"light":"github-light","dark":"vesper"}}
require "resend"

Resend.api_key = "re_xxxxxxxxx"

params = {
  event: "payment.failed",
  contact_id: "e169aa45-1ecf-4183-9955-b1499d5701d3",
  payload: {
    amount: 49.99,
    currency: "USD",
    retryDate: "2026-11-01",
  },
}

Resend::Events.send(params)
```

```go Go {11-15} theme={"theme":{"light":"github-light","dark":"vesper"}}
package main

import "github.com/resend/resend-go/v4"

func main() {
	client := resend.NewClient("re_xxxxxxxxx")

	client.Events.Send(&resend.SendEventRequest{
		Event:     "payment.failed",
		ContactId: "e169aa45-1ecf-4183-9955-b1499d5701d3",
		Payload: map[string]any{
			"amount":    49.99,
			"currency":  "USD",
			"retryDate": "2026-11-01",
		},
	})
}
```

```rust Rust {18-22} theme={"theme":{"light":"github-light","dark":"vesper"}}
use resend_rs::{
  json,
  types::{ContactIdOrEmail, SendEventOptions},
  Resend, Result,
};

#[tokio::main]
async fn main() -> Result<()> {
  let resend = Resend::new("re_xxxxxxxxx");

  let _event = resend
    .events
    .send(SendEventOptions {
      event: "payment.failed".to_owned(),
      contact_id_or_email: ContactIdOrEmail::ContactId(
        "e169aa45-1ecf-4183-9955-b1499d5701d3".to_owned(),
      ),
      payload: json!({
        "amount": 49.99,
        "currency": "USD",
        "retryDate": "2026-11-01"
      }),
    })
    .await?;

  Ok(())
}
```

```java Java {11-13} theme={"theme":{"light":"github-light","dark":"vesper"}}
import com.resend.*;
import com.resend.core.exception.ResendException;
import com.resend.services.events.model.*;

public class Main {
    public static void main(String[] args) throws ResendException {
        Resend resend = new Resend("re_xxxxxxxxx");

        SendEventOptions params = SendEventOptions.builder()
                .event("payment.failed")
                .contactId("e169aa45-1ecf-4183-9955-b1499d5701d3")
                .addPayload("amount", 49.99)
                .addPayload("currency", "USD")
                .addPayload("retryDate", "2026-11-01")
                .build();

        SendEventResponseSuccess data = resend.events().send(params);
    }
}
```

```csharp .NET {6-11} theme={"theme":{"light":"github-light","dark":"vesper"}}
using Resend;
using System.Text.Json;

IResend resend = ResendClient.Create( "re_xxxxxxxxx" );

var payload = JsonSerializer.SerializeToElement( new
{
    amount = 49.99,
    currency = "USD",
    retryDate = "2026-11-01",
} );

var resp = await resend.EventSendAsync( new EventSendData()
{
    Event = "payment.failed",
    ContactId = new Guid( "e169aa45-1ecf-4183-9955-b1499d5701d3" ),
    Payload = payload,
} );
```

```bash cURL {7-11} theme={"theme":{"light":"github-light","dark":"vesper"}}
curl -X POST 'https://api.resend.com/events/send' \
     -H 'Authorization: Bearer re_xxxxxxxxx' \
     -H 'Content-Type: application/json' \
     -d '{
  "event": "payment.failed",
  "contact_id": "xxxxxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxxx",
  "payload": {
    "amount": 49.99,
    "currency": "USD",
    "retryDate": "2026-11-01"
  }
}'
```

```bash CLI theme={"theme":{"light":"github-light","dark":"vesper"}}
resend events send \
  --event payment.failed \
  --contact-id e169aa45-1ecf-4183-9955-b1499d5701d3 \
  --payload '{"amount":49.99,"currency":"USD","retryDate":"2026-11-01"}'
```
:::

In this example, you can use `event.amount`, `event.currency`, and `event.retryDate` in other automation [conditions](/guides/learn-dashboard-automations-condition) and steps, or in email templates.

View the [Send Event API reference](/guides/events-send-event) for the full endpoint specification.

## Configuration

- `config.event_name` (string, required) — The name of the event that triggers the automation.

```json theme={"theme":{"light":"github-light","dark":"vesper"}}
{
  "key": "start",
  "type": "trigger",
  "config": {
    "event_name": "user.created"
  }
}
```

## Related pages

- [Steps](./learn-dashboard-automations-steps.md)
- [Condition](./learn-dashboard-automations-condition.md)
- [Delay](./learn-dashboard-automations-delay.md)
- [Wait for Event](./learn-dashboard-automations-wait-for-event.md)
- [Send Email](./learn-dashboard-automations-send-email.md)
- [Add to Segment](./learn-dashboard-automations-add-to-segment.md)
- [Contact Update](./learn-dashboard-automations-contact-update.md)
- [Contact Delete](./learn-dashboard-automations-contact-delete.md)

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