Use webhooks ↗

Documentation Index#

Fetch the complete documentation index at: https://docs.langchain.com/llms.txt Use this file to discover all available pages before exploring further.

Webhooks enable event-driven communication from your LangSmith application to external services. For example, you may want to issue an update to a separate service once an API call to LangSmith has finished running.

Many LangSmith endpoints accept a webhook parameter. If this parameter is specified by an endpoint that can accept POST requests, LangSmith will send a request at the completion of a run.

When working with LangSmith, you may want to use webhooks to receive updates after an API call completes. Webhooks are useful for triggering actions in your service once a run has finished processing. To implement this, you need to expose an endpoint that can accept POST requests and pass this endpoint as a webhook parameter in your API request.

Currently, the SDK does not provide built-in support for defining webhook endpoints, but you can specify them manually using API requests.

Supported endpoints#

The following API endpoints accept a webhook parameter:

In this guide, we’ll show how to trigger a webhook after streaming a run.

Set up your assistant and thread#

Before making API calls, set up your assistant and thread.

    from langgraph_sdk import get_client

    client = get_client(url=<DEPLOYMENT_URL>)
    assistant_id = "agent"
    thread = await client.threads.create()
    print(thread)
    ```
  <span class="tab-end"></span>

  <span class="tab-start" data-tab-title="JavaScript"></span>
```js
    import { Client } from "@langchain/langgraph-sdk";

    const client = new Client({ apiUrl: <DEPLOYMENT_URL> });
    const assistantID = "agent";
    const thread = await client.threads.create();
    console.log(thread);
    ```
  <span class="tab-end"></span>

  <span class="tab-start" data-tab-title="CURL"></span>
```bash
    curl --request POST \
        --url <DEPLOYMENT_URL>/assistants/search \
        --header 'Content-Type: application/json' \
        --data '{ "limit": 10, "offset": 0 }' | jq -c 'map(select(.config == null or .config == {})) | .[0]' && \
    curl --request POST \
        --url <DEPLOYMENT_URL>/threads \
        --header 'Content-Type: application/json' \
        --data '{}'
    ```
  <span class="tab-end"></span>
<span class="tab-group-end"></span>

Example response:

```json
{
    "thread_id": "9dde5490-2b67-47c8-aa14-4bfec88af217",
    "created_at": "2024-08-30T23:07:38.242730+00:00",
    "updated_at": "2024-08-30T23:07:38.242730+00:00",
    "metadata": {},
    "status": "idle",
    "config": {},
    "values": null
}

Use a webhook with a graph run#

To use a webhook, specify the webhook parameter in your API request. When the run completes, LangSmith sends a POST request to the specified webhook URL.

For example, if your server listens for webhook events at https://my-server.app/my-webhook-endpoint, include this in your request:

    input = { "messages": [{ "role": "user", "content": "Hello!" }] }

    async for chunk in client.runs.stream(
        thread_id=thread["thread_id"],
        assistant_id=assistant_id,
        input=input,
        stream_mode="events",
        webhook="https://my-server.app/my-webhook-endpoint"
    ):
        pass
    ```
  <span class="tab-end"></span>

  <span class="tab-start" data-tab-title="JavaScript"></span>
```js
    const input = { messages: [{ role: "human", content: "Hello!" }] };

    const streamResponse = client.runs.stream(
      thread["thread_id"],
      assistantID,
      {
        input: input,
        webhook: "https://my-server.app/my-webhook-endpoint"
      }
    );

    for await (const chunk of streamResponse) {
      // Handle stream output
    }
    ```
  <span class="tab-end"></span>

  <span class="tab-start" data-tab-title="CURL"></span>
```bash
    curl --request POST \
        --url <DEPLOYMENT_URL>/threads/<THREAD_ID>/runs/stream \
        --header 'Content-Type: application/json' \
        --data '{
            "assistant_id": <ASSISTANT_ID>,
            "input": {"messages": [{"role": "user", "content": "Hello!"}]},
            "webhook": "https://my-server.app/my-webhook-endpoint"
        }'
    ```
  <span class="tab-end"></span>
<span class="tab-group-end"></span>

## Webhook payload

LangSmith sends webhook notifications in the format of a [Run](/langsmith/assistants#execution). See the [API Reference](https://docs.langchain.com/langsmith/server-api-ref#tag/assistants) for details. The request payload includes run input, configuration, and other metadata in the `kwargs` field.

## Secure webhooks

To ensure only authorized requests hit your webhook endpoint, consider adding a security token as a query parameter:

https://my-server.app/my-webhook-endpoint?token=YOUR_SECRET_TOKEN

Your server should extract and validate this token before processing requests.

## Add headers to webhook requests

<span class="callout-start" data-callout-type="note"></span>
  Available in `langgraph-api>=0.5.36`.
<span class="callout-end"></span>

You can configure static headers to include with all outbound webhook requests. This is useful for authentication, routing, or passing metadata to your webhook endpoint.

Add a `webhooks.headers` configuration to your `langgraph.json` file:

```json
{
  "webhooks": {
    "headers": {
      "X-Custom-Header": "my-value",
      "X-Environment": "production"
    }
  }
}

Use environment variables in headers#

To include secrets or environment-specific values without checking them into your configuration file, use the ${{ env.VAR }} template syntax:

{
  "webhooks": {
    "headers": {
      "Authorization": "Bearer ${{ env.LG_WEBHOOK_TOKEN }}"
    }
  }
}

For security, only environment variables starting with LG_WEBHOOK_ can be referenced by default. This prevents accidentally leaking unrelated environment variables. You can customize this prefix using env_prefix:

{
  "webhooks": {
    "env_prefix": "MY_APP_",
    "headers": {
      "Authorization": "Bearer ${{ env.MY_APP_SECRET }}"
    }
  }
}

Missing required environment variables will block server startup, ensuring you don’t deploy with incomplete configuration.

Restrict webhook destinations#

Available in langgraph-api>=0.5.36.

For security or compliance purposes, you can restrict which URLs are valid webhook destinations using the webhooks.url configuration:

{
  "webhooks": {
    "url": {
      "allowed_domains": ["*.mycompany.com", "api.trusted-service.com"],
      "require_https": true
    }
  }
}

Available options:

Disable webhooks#

As of langgraph-api>=0.2.78, developers can disable webhooks in the langgraph.json file:

{
  "http": {
    "disable_webhooks": true
  }
}

This feature is primarily intended for self-hosted deployments, where platform administrators or developers may prefer to disable webhooks to simplify their security posture—especially if they are not configuring firewall rules or other network controls. Disabling webhooks helps prevent untrusted payloads from being sent to internal endpoints.

For full configuration details, refer to the configuration file reference.

Test webhooks#

You can test your webhook using online services like:

• Beeceptor – Quickly create a test endpoint and inspect incoming webhook payloads.
• Webhook.site – View, debug, and log incoming webhook requests in real time.

These tools help you verify that LangSmith is correctly triggering and sending webhooks to your service.

Edit this page on GitHub or file an issue.

Connect these docs to Claude, VSCode, and more via MCP for real-time answers.