> ## Documentation Index
> Fetch the complete documentation index at: https://resend.com/docs/llms.txt
> Use this file to discover all available pages before exploring further.
# Contact properties
> Learn how to work with Contact properties with Resend.
## Contact properties
Contact properties can be used to store additional information about your Contacts and then [personalize your Broadcasts](#use-contact-properties-in-broadcasts) with dynamic content.
## Included properties
Each Contact includes the following attributes:
* `email`: The email address of the Contact. (required)
* `first_name`: The first name of the Contact.
* `last_name`: The last name of the Contact.
* `segments`: A list of [Segments](/docs/dashboard/contacts/introduction#segments) the Contact belongs to.
* `topics`: A list of [Topics](/docs/dashboard/contacts/introduction#topics) the Contact subscribes to.
* `unsubscribed`: Whether the Contact is unsubscribed from all Broadcasts.
* `properties`: An object of custom-defined properties, where each value includes the property's `value` and `type`.
## Manage Contact properties
You can view, add, and manage your Contact properties in the [**Properties** Dashboard view](https://resend.com/audience/properties) or programmatically with the [Contact properties API](/docs/api-reference/contact-properties/create-contact-property), [Resend CLI commands](/docs/cli#contact-properties), and [MCP](/docs/mcp-server).
You can also create [Automations](/docs/dashboard/automations/introduction) to update Contact properties.
## Add Custom Contact properties
You can create additional custom Contact properties for your Contacts to store additional information. These properties can be used to personalize your Broadcasts across all Segments.
Each Contact Property has a key, a value, and optional fallback value.
* `key`: The key of the property (must be alphanumeric and underscore only, max 50 characters). This is case sensitive.
* `value`: The value of the property (may be a `string` or `number`).
* `fallback_value`: The fallback value of the property (must match the type of the property).
You can also create Contact properties [via the API or SDKs](/docs/api-reference/contact-properties/create-contact-property).
```ts Node.js theme={"theme":{"light":"github-light","dark":"vesper"}}
import { Resend } from 'resend';
const resend = new Resend('re_xxxxxxxxx');
const { data, error } = await resend.contactProperties.create({
key: 'company_name',
type: 'string',
fallbackValue: 'Acme Corp',
});
```
```php PHP theme={"theme":{"light":"github-light","dark":"vesper"}}
$resend = Resend::client('re_xxxxxxxxx');
$resend->contactProperties->create([
'key' => 'company_name',
'type' => 'string',
'fallback_value' => 'Acme Corp',
]);
```
```python Python theme={"theme":{"light":"github-light","dark":"vesper"}}
import resend
resend.api_key = 're_xxxxxxxxx'
params: resend.ContactProperties.CreateParams = {
"key": "company_name",
"type": "string",
"fallback_value": "Acme Corp",
}
contact_property = resend.ContactProperties.create(params)
```
```ruby Ruby theme={"theme":{"light":"github-light","dark":"vesper"}}
require "resend"
Resend.api_key = "re_xxxxxxxxx"
property = Resend::ContactProperties.create({
key: "company_name",
type: "string",
fallback_value: "Acme Corp"
})
```
```go Go theme={"theme":{"light":"github-light","dark":"vesper"}}
package main
import (
"context"
"fmt"
"github.com/resend/resend-go/v4"
)
func main() {
ctx := context.TODO()
apiKey := "re_xxxxxxxxx"
client := resend.NewClient(apiKey)
params := &resend.CreateContactPropertyRequest{
Key: "company_name",
Type: "string",
FallbackValue: "Acme Corp",
}
property, err := client.ContactProperties.CreateWithContext(ctx, params)
if err != nil {
panic(err)
}
fmt.Println(property)
}
```
```rust Rust theme={"theme":{"light":"github-light","dark":"vesper"}}
use resend_rs::{
types::{CreateContactPropertyOptions, PropertyType},
Resend, Result,
};
#[tokio::main]
async fn main() -> Result<()> {
let resend = Resend::new("re_xxxxxxxxx");
let contact_property = CreateContactPropertyOptions::new("company_name", PropertyType::String)
.with_fallback("Acme Corp");
let _contact_property = resend.contacts.create_property(contact_property).await?;
Ok(())
}
```
```java Java theme={"theme":{"light":"github-light","dark":"vesper"}}
import com.resend.*;
import com.resend.core.exception.ResendException;
import com.resend.services.contactproperties.model.CreateContactPropertyOptions;
public class Main {
public static void main(String[] args) throws ResendException {
Resend resend = new Resend("re_xxxxxxxxx");
CreateContactPropertyOptions options = CreateContactPropertyOptions.builder()
.key("company_name")
.type("string")
.fallbackValue("Acme Corp")
.build();
resend.contactProperties().create(options);
}
}
```
```csharp .NET theme={"theme":{"light":"github-light","dark":"vesper"}}
using Resend;
IResend resend = ResendClient.Create( "re_xxxxxxxxx" ); // Or from DI
var resp = await resend.ContactPropCreateAsync( new ContactPropertyData() {
Key = "company_name",
PropertyType = ContactPropertyType.String,
DefaultValue = "Acme Corp",
} );
Console.WriteLine( "Prop Id={0}", resp.Content );
```
```bash cURL theme={"theme":{"light":"github-light","dark":"vesper"}}
curl -X POST 'https://api.resend.com/contact-properties' \
-H 'Authorization: Bearer re_xxxxxxxxx' \
-H 'Content-Type: application/json' \
-d $'{
"key": "company_name",
"type": "string",
"fallback_value": "Acme Corp"
}'
```
## Add properties to a Contact
When you create a Contact property with a fallback value, that default is used for Contacts that do not have a custom value for the property. If no fallback is provided, the Contact will not have a value for that property.
To update this value for a Contact in the [Dashboard](https://resend.com/audience):
## Add or update property values programmatically
You can add custom property values to a Contact when you [create a Contact with the API](/docs/api-reference/contacts/create-contact) or [from the terminal with a CLI command](/docs/cli#contacts).
```ts Node.js {10-12} theme={"theme":{"light":"github-light","dark":"vesper"}}
import { Resend } from 'resend';
const resend = new Resend('re_xxxxxxxxx');
const { data, error } = await resend.contacts.create({
email: 'steve.wozniak@gmail.com',
firstName: 'Steve',
lastName: 'Wozniak',
unsubscribed: false,
properties: {
company_name: 'Acme Corp',
},
});
```
```php PHP {9-11} theme={"theme":{"light":"github-light","dark":"vesper"}}
$resend = Resend::client('re_xxxxxxxxx');
$resend->contacts->create(
parameters: [
'email' => 'steve.wozniak@gmail.com',
'first_name' => 'Steve',
'last_name' => 'Wozniak',
'unsubscribed' => false,
'properties' => [
'company_name' => 'Acme Corp',
]
]
);
```
```python Python {10-12} theme={"theme":{"light":"github-light","dark":"vesper"}}
import resend
resend.api_key = "re_xxxxxxxxx"
params: resend.Contacts.CreateParams = {
"email": "steve.wozniak@gmail.com",
"first_name": "Steve",
"last_name": "Wozniak",
"unsubscribed": False,
"properties": {
"company_name": "Acme Corp"
}
}
resend.Contacts.create(params)
```
```ruby Ruby {10-12} theme={"theme":{"light":"github-light","dark":"vesper"}}
require "resend"
Resend.api_key = "re_xxxxxxxxx"
params = {
"email": "steve.wozniak@gmail.com",
"first_name": "Steve",
"last_name": "Wozniak",
"unsubscribed": false,
"properties": {
"company_name": "Acme Corp",
}
}
Resend::Contacts.create(params)
```
```go Go {10-12} theme={"theme":{"light":"github-light","dark":"vesper"}}
import "github.com/resend/resend-go/v4"
client := resend.NewClient("re_xxxxxxxxx")
params := &resend.CreateContactRequest{
Email: "steve.wozniak@gmail.com",
FirstName: "Steve",
LastName: "Wozniak",
Unsubscribed: false,
Properties: map[string]interface{} {
"company_name": "Acme Corp",
},
}
client.Contacts.Create(params)
```
```rust Rust {12-15} theme={"theme":{"light":"github-light","dark":"vesper"}}
use resend_rs::{types::CreateContactOptions, Resend, Result};
use std::collections::HashMap;
#[tokio::main]
async fn main() -> Result<()> {
let resend = Resend::new("re_xxxxxxxxx");
let contact = CreateContactOptions::new("steve.wozniak@gmail.com")
.with_first_name("Steve")
.with_last_name("Wozniak")
.with_unsubscribed(false)
.with_properties(HashMap::from([(
"company_name".to_string(),
"Acme Corp".to_string(),
)]));
let _contact = resend.contacts.create(contact).await?;
Ok(())
}
```
```java Java {15-16} theme={"theme":{"light":"github-light","dark":"vesper"}}
import com.resend.*;
import com.resend.core.exception.ResendException;
import com.resend.services.contacts.model.CreateContactOptions;
import com.resend.services.contacts.model.CreateContactResponseSuccess;
public class Main {
public static void main(String[] args) throws ResendException {
Resend resend = new Resend("re_xxxxxxxxx");
CreateContactOptions params = CreateContactOptions.builder()
.email("steve.wozniak@gmail.com")
.firstName("Steve")
.lastName("Wozniak")
.unsubscribed(false)
.properties(java.util.Map.of("company_name", "Acme Corp"))
.build();
CreateContactResponseSuccess data = resend.contacts().create(params);
}
}
```
```csharp .NET {12-14} theme={"theme":{"light":"github-light","dark":"vesper"}}
using Resend;
IResend resend = ResendClient.Create( "re_xxxxxxxxx" ); // Or from DI
var resp = await resend.ContactAddAsync(
new ContactData()
{
Email = "steve.wozniak@gmail.com",
FirstName = "Steve",
LastName = "Wozniak",
IsUnsubscribed = false,
Properties = new Dictionary {
{ "company_name", "Acme Corp" }
}
}
);
Console.WriteLine( "Contact Id={0}", resp.Content );
```
```bash cURL {9-11} theme={"theme":{"light":"github-light","dark":"vesper"}}
curl -X POST 'https://api.resend.com/contacts' \
-H 'Authorization: Bearer re_xxxxxxxxx' \
-H 'Content-Type: application/json' \
-d $'{
"email": "steve.wozniak@gmail.com",
"first_name": "Steve",
"last_name": "Wozniak",
"unsubscribed": false,
"properties": {
"company_name": "Acme Corp",
}
}'
```
You can also update a Contact to add or change a property value [using the update Contact endpoint](/docs/api-reference/contacts/update-contact) or [CLI command](/docs/cli#contacts).
```ts Node.js {8-10} theme={"theme":{"light":"github-light","dark":"vesper"}}
import { Resend } from 'resend';
const resend = new Resend('re_xxxxxxxxx');
const { data, error } = await resend.contacts.update({
id: 'e169aa45-1ecf-4183-9955-b1499d5701d3',
// or: email: 'acme@example.com',
properties: {
company_name: 'Acme Corp',
},
});
```
```php PHP {7-9, 17-19} theme={"theme":{"light":"github-light","dark":"vesper"}}
$resend = Resend::client('re_xxxxxxxxx');
// Update by contact id
$resend->contacts->update(
idOrEmail: 'e169aa45-1ecf-4183-9955-b1499d5701d3',
parameters: [
'properties' => [
'company_name' => 'Acme Corp',
]
]
);
// Update by contact email
$resend->contacts->update(
idOrEmail: 'acme@example.com',
parameters: [
'properties' => [
'company_name' => 'Acme Corp',
]
]
);
```
```python Python {8-10, 18-20} theme={"theme":{"light":"github-light","dark":"vesper"}}
import resend
resend.api_key = "re_xxxxxxxxx"
# Update by contact id
params: resend.Contacts.UpdateParams = {
"id": "e169aa45-1ecf-4183-9955-b1499d5701d3",
"properties": {
"company_name": "Acme Corp",
}
}
resend.Contacts.update(params)
# Update by contact email
params: resend.Contacts.UpdateParams = {
"email": "acme@example.com",
"properties": {
"company_name": "Acme Corp",
}
}
resend.Contacts.update(params)
```
```ruby Ruby {8-10, 18-20} theme={"theme":{"light":"github-light","dark":"vesper"}}
require "resend"
Resend.api_key = "re_xxxxxxxxx"
# Update by contact id
params = {
"id": "e169aa45-1ecf-4183-9955-b1499d5701d3",
"properties": {
"company_name": "Acme Corp",
}
}
Resend::Contacts.update(params)
# Update by contact email
params = {
"email": "acme@example.com",
"properties": {
"company_name": "Acme Corp",
}
}
Resend::Contacts.update(params)
```
```go Go {8-10, 19-21} theme={"theme":{"light":"github-light","dark":"vesper"}}
import "github.com/resend/resend-go/v4"
client := resend.NewClient("re_xxxxxxxxx")
// Update by contact id
params := &resend.UpdateContactRequest{
Id: "e169aa45-1ecf-4183-9955-b1499d5701d3",
Properties: map[string]interface{}{
"company_name": "Acme Corp",
},
}
params.SetUnsubscribed(true)
client.Contacts.Update(params)
// Update by contact email
params = &resend.UpdateContactRequest{
Email: "acme@example.com",
Properties: map[string]interface{}{
"company_name": "Acme Corp",
},
}
params.SetUnsubscribed(true)
client.Contacts.Update(params)
```
```rust Rust {8-11} theme={"theme":{"light":"github-light","dark":"vesper"}}
use resend_rs::{types::ContactChanges, Resend, Result};
use std::collections::HashMap;
#[tokio::main]
async fn main() -> Result<()> {
let resend = Resend::new("re_xxxxxxxxx");
let changes = ContactChanges::new().with_properties(HashMap::from([(
"company_name".to_string(),
"Acme Corp".to_string(),
)]));
// Update by contact id
let _contact = resend
.contacts
.update("e169aa45-1ecf-4183-9955-b1499d5701d3", changes.clone())
.await?;
// Update by contact email
let _contact = resend
.contacts
.update("acme@example.com", changes)
.await?;
Ok(())
}
```
```java Java {12} theme={"theme":{"light":"github-light","dark":"vesper"}}
import com.resend.*;
import com.resend.core.exception.ResendException;
import com.resend.services.contacts.model.UpdateContactOptions;
import com.resend.services.contacts.model.UpdateContactResponseSuccess;
public class Main {
public static void main(String[] args) throws ResendException {
Resend resend = new Resend("re_xxxxxxxxx");
UpdateContactOptions params = UpdateContactOptions.builder()
.id("e169aa45-1ecf-4183-9955-b1499d5701d3") // or: .email("acme@example.com")
.properties(java.util.Map.of("company_name", "Acme Corp"))
.build();
UpdateContactResponseSuccess data = resend.contacts().update(params);
}
}
```
```csharp .NET {12-14, 25-27} theme={"theme":{"light":"github-light","dark":"vesper"}}
using Resend;
IResend resend = ResendClient.Create( "re_xxxxxxxxx" ); // Or from DI
// By Id
await resend.ContactUpdateAsync(
contactId: new Guid( "e169aa45-1ecf-4183-9955-b1499d5701d3" ),
new ContactData()
{
FirstName = "Stevie",
LastName = "Wozniaks",
Properties = new Dictionary {
{ "company_name", "Acme Corp" }
}
}
);
// By Email
await resend.ContactUpdateByEmailAsync(
"acme@example.com",
new ContactData()
{
FirstName = "Stevie",
LastName = "Wozniaks",
Properties = new Dictionary {
{ "company_name", "Acme Corp" }
}
}
);
```
```bash cURL {6-8, 16-18} theme={"theme":{"light":"github-light","dark":"vesper"}}
# Update by contact id
curl -X PATCH 'https://api.resend.com/contacts/520784e2-887d-4c25-b53c-4ad46ad38100' \
-H 'Authorization: Bearer re_xxxxxxxxx' \
-H 'Content-Type: application/json' \
-d $'{
"properties": {
"company_name": "Acme Corp",
}
}'
# Update by contact email
curl -X PATCH 'https://api.resend.com/contacts/acme@example.com' \
-H 'Authorization: Bearer re_xxxxxxxxx' \
-H 'Content-Type: application/json' \
-d $'{
"properties": {
"company_name": "Acme Corp",
}
}'
```
When you create or update a Contact with properties, the properties are added to the Contact only if the property key already exists and the value type is valid.
If the properties don't exist, or the values are of the wrong type, they are not added to the Contact and the call fails. An error is returned.
You can [list all Contact properties with the API](/docs/api-reference/contact-properties/list-contact-properties) to see and verify all available properties.
## Use Contact properties in Broadcasts
You can use Contact properties in your Broadcasts to [personalize your emails](/docs/dashboard/broadcasts/editor#personalize-your-content).
You can also use Contact properties in your Broadcast HTML and Text content when you [create a Broadcast using the API or SDKs](/docs/api-reference/broadcasts/create-broadcast).
## API Reference
For complete API documentation, see the [Contact properties API reference](/docs/api-reference/contact-properties/create-contact-property).