> ## Documentation Index
> Fetch the complete documentation index at: https://docs.trysignal.ai/llms.txt
> Use this file to discover all available pages before exploring further.

# Set person properties

> Set user properties with setPersonProperties and setPersonPropertiesOnce

# Node — Set person properties

Set or update user properties from the server with `setPersonProperties` (overwrites) or `setPersonPropertiesOnce` (only if not already set). Pass `sessionId` and `windowId` when correlating with the client session.

## setPersonProperties(distinctId, properties, sessionId?, windowId?)

Sets user properties (overwrites). Sends `$set` event.

| Parameter    | Type         | Required | Description                                              |
| ------------ | ------------ | -------- | -------------------------------------------------------- |
| `distinctId` | `string`     | yes      | User identifier                                          |
| `properties` | `UserTraits` | yes      | User properties to set or update                         |
| `sessionId`  | `string`     | no       | From `x-signal-session-id` header for client correlation |
| `windowId`   | `string`     | no       | From `x-signal-window-id` header for client correlation  |

**When to use:** Update user properties without sending an `$identify` event (e.g. when properties change after initial identification).

```typescript theme={null}
const { sessionId, windowId, distinctId } = getSessionInfo(req);

signal.setPersonProperties(
  distinctId || userId,
  { plan: 'pro', role: 'admin' },
  sessionId,
  windowId
);
```

## setPersonPropertiesOnce(distinctId, properties, sessionId?, windowId?)

Sets user properties only if not already set. Sends `$set_once` event.

| Parameter    | Type         | Required | Description                                              |
| ------------ | ------------ | -------- | -------------------------------------------------------- |
| `distinctId` | `string`     | yes      | User identifier                                          |
| `properties` | `UserTraits` | yes      | User properties to set (only if not already set)         |
| `sessionId`  | `string`     | no       | From `x-signal-session-id` header for client correlation |
| `windowId`   | `string`     | no       | From `x-signal-window-id` header for client correlation  |

**When to use:** One-time attributes that shouldn't be overwritten (e.g. `signupSource`, `firstPurchaseDate`).

```typescript theme={null}
const { sessionId, windowId, distinctId } = getSessionInfo(req);

signal.setPersonPropertiesOnce(
  distinctId || userId,
  { signupSource: 'organic' },
  sessionId,
  windowId
);
```

## See also

* [Identify](/docs/integrations/node/identify) — identify()
* [Capture](/docs/integrations/node/capture) — capture()