Context

The NLX Context API is a specialized endpoint that asynchronously sets session attributes for an active NLX conversation, with special capabilities for Voice+.

Unlike the Track API (which tracks journey steps), the Context API allows you to push detailed metadata about the current page, such as available form fields, current values, and navigation URLs, so the Voice AI knows exactly what the user is looking at.

When to use this API

Form filling

Tell the Voice AI what fields are on the screen (e.g., "Account Number", "Amount") so it can offer to fill them

Navigation awareness

Update the Voice AI when the user navigates to a new URL

State synchronization

Send current field values to the Voice+ app if the user manually types them in

Context updates

Update the context of your conversation asynchronously

Configuration

This endpoint is part of the standard Conversation API suite and shares the same authentication.

Setting	Value
Base URL	https://apps.nlx.ai/c/{deploymentKey}/{channelKey}-{languageCode}/context
Header	nlx-api-key: YOUR_API_KEY

Ensure you append /context to the standard base URL.

Send context (POST)

Push a context payload to the active conversation.

Endpoint: POST /context

Request body

Field	Type	Required	Description
conversationId	String	Yes	The active voice session ID.
context	Object	Yes	Wrapper for context data.
context.nlx:vpContext	Object	Yes	The specific Voice+ context container.

Example: Form fields

In this example, the web app tells the Voice AI that the user is on a "Transfer" page with fields for Account and Amount.

curl -X POST "https://apps.nlx.ai/c/YOUR_DEPLOYMENT_KEY/YOUR_CHANNEL_KEY-en-US/context" \
  -H "nlx-api-key: YOUR_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{
    "conversationId": "c03e0066-7cba-4bbf-b60b-10109b95a9f6",
    "context": {
      "nlx:vpContext": {
        "uri": "https://mybank.com/transfer",
        "fields": [
          {
            "id": "toAccount",
            "name": "To Account",
            "type": "select",
            "description": "Destination account",
            "value": "1131"
          },
          {
            "id": "amount",
            "name": "Transfer Amount",
            "type": "number",
            "description": "Amount in USD",
            "placeholder": "Enter amount"
          }
        ],
        "scopes": ["home_page"]
      }
    }
  }'

Response

The server responds with a 200 OK empty JSON object upon success.

{}