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

# context.notify

`context.notify()` notifies workflows that are waiting for a specific event, passing along an optional payload.

It is typically used in combination with [`context.waitForEvent`](/workflow/basics/context#context-waitforevent).

## Arguments

<ParamField body="stepName" type="string">
  A unique identifier for the step.
</ParamField>

<ParamField body="eventId" type="string">
  The identifier of the event to notify.
  Must match the `eventId` used in `context.waitForEvent`.
</ParamField>

<ParamField body="eventData" type="any">
  Data to deliver to the waiting workflow(s).
  This value will be returned in `eventData` from the corresponding `waitForEvent` call.
</ParamField>

<ParamField body="workflowRunId" type="string" optional>
  The workflow run ID to notify. When provided, enables **lookback functionality** - the notification will be stored and delivered even if `notify` is called before `waitForEvent`.

  This solves race conditions where notifications might be sent before a workflow reaches its wait step.
</ParamField>

## Response

`context.notify()` returns a list of waiters describing the workflows that were notified.

<ResponseField name="notifyResponse" type="NotifyResponse[]">
  A list of `NotifyResponse` objects describing each workflow that was waiting on the event.

  <Expandable defaultOpen>
    <ResponseField name="messageId" type="string">
      The ID of the notification message delivered to the workflow.
      This is unique to every notification.
    </ResponseField>

    <ResponseField name="workflowRunId" type="string">
      The unique identifier of the workflow run that was notified.
    </ResponseField>

    <ResponseField name="workflowCreatedAt" type="number">
      Unix timestamp (in milliseconds) representing when the workflow was created.
    </ResponseField>

    <Snippet file="qstash/waiter.mdx" />
  </Expandable>
</ResponseField>

## Usage

### Basic Notification

```javascript theme={"system"}
import { serve } from "@upstash/workflow/nextjs";

export const { POST } = serve<{ topic: string }>(async (context) => {
  const payload = context.requestPayload;

  const {
    notifyResponse, // result of notify, which is a list of notified waiters
  } = await context.notify("notify step", "my-event-Id", payload);
});
```

### Notification with Lookback

To prevent race conditions, you can provide a `workflowRunId`. This enables lookback - the notification will be stored and delivered even if sent before the target workflow reaches `waitForEvent`:

```javascript theme={"system"}
import { serve } from "@upstash/workflow/nextjs";

export const { POST } = serve<{ orderId: string }>(async (context) => {
  const { orderId } = context.requestPayload;

  // Process payment
  await context.run("process-payment", async () => {
    return processPayment(orderId);
  });

  // Notify a specific workflow run with lookback support
  const {
    notifyResponse,
  } = await context.notify(
    "notify payment complete",
    "payment-processed",
    { orderId, status: "success" },
    "wfr_order_processor_123" // Enables lookback for this workflow run
  );
});
```