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Signal Trigger

The Signal trigger enables communication between multiple workflows. One workflow sends a signal, and another workflow receives it and starts automatically — no human intervention needed.

Signal Trigger

Core Concept​

The Signal trigger is essentially one-to-many broadcast communication: the sender broadcasts a signal ID via the Send Signal node, and all Signal triggers listening for that ID will receive it and start. A single signal can wake up multiple workflows simultaneously.

Signals can carry data. Data attached by the sender is automatically JSON-parsed and, upon success, stored in the variable configured on the receiver side.

Configuration Steps​

Take two workflows as an example — Workflow A sends a signal, Workflow B receives it and shows a notification.

Workflow A (Sender): Manual Execute → Send Signal

Signal Trigger Example - Workflow A
  1. Drag in Manual Execute as the entry point
  2. Drag in the Send Signal node
  3. Fill in a signal ID, e.g., order_updated

Workflow B (Receiver): Signal Trigger → Show Notification

Signal Trigger Example - Workflow B
  1. Drag in the "Signal Trigger" node, set Signal ID to order_updated (must match the sender exactly)
  2. Set the variable name for received data (the execution page is controlled by system reserved fields in the signal — see below)
  3. Drag in the Show Notification node
  4. After saving, when Workflow A executes, Workflow B will automatically receive the signal and start

Execution Page Control​

The Signal trigger's execution page is entirely determined by system reserved fields in the received signal data — the trigger itself no longer has a separate execution mode setting. The sender includes the following reserved fields in the signal JSON data to control which page the workflow executes on:

FieldDescription
_target_urlNavigate to this URL and execute the workflow.
_target_tab_idExecute the workflow in a specified already-opened tab.
(No reserved fields)When no reserved fields are included, the workflow executes on the signal sender's page.

Priority: _target_tab_id > _target_url. If both are present, _target_tab_id is used.

// Example: sending a signal with _target_url
{
  "orderId": 12345,
  "_target_url": "https://example.com/orders/12345"
}

Parameter Reference​

Signal ID​

The unique identifier for the signal. Must match exactly between sender and receiver (case-sensitive). Use meaningful English names:

order_updated          → Order has been updated
data_sync_complete     → Data sync completed
crawl_finished         → Crawling finished

Receive Data​

The variable name to store the sender's attached data after automatic JSON parsing. For example, if set to data, subsequent nodes can reference the received content using {{data}}.

If the sender doesn't include data, or the data isn't valid JSON, the variable value remains as-is (a string).

Activate Tab​

When enabled, the browser automatically switches focus to the tab running the workflow when a signal is received. Suitable for scenarios where the user needs to see the operation results on the page; can be turned off for pure background data processing.

Use Cases​

Signal trigger is ideal for multi-workflow orchestration scenarios:

  • After a login workflow completes, send a signal — the data scraping workflow receives it and starts fetching data
  • A scheduled inspection workflow detects an anomaly and sends a signal — the notification workflow receives it and pops up an alert
  • A main workflow is split into multiple sub-workflows running in parallel, using signals to chain execution order

FAQ​

Signal trigger keeps waiting and never starts​

Symptom: The workflow never starts, and the log shows "waiting for signal."

Cause: The signal ID is spelled inconsistently (case-sensitive), or the sender workflow hasn't executed yet.

Solution: Check whether the signal IDs on the sender and receiver match exactly, including case. First trigger the sender manually using "Manual Execute" to confirm the signal is actually sent.