Loop Node

The loop node iterates over data, executing a set of nodes for each iteration. It supports three modes: iterating over arrays, running a fixed count, or looping while a condition is true.

Configuration

{
  "id": "process_orders",
  "type": "loop",
  "config": {
    "items": "{{request.body.orders}}",
    "as": "order",
    "index": "i",
    "do": ["validate_order", "process_order"],
    "concurrent": false
  }
}

Config Fields

Field	Type	Required	Default	Description
`items`	string	*	-	Template resolving to an array
`count`	number/string	*	-	Number of iterations or template
`while`	string	*	-	Condition to check each iteration
`max`	number	**	-	Maximum iterations (required for `while`)
`as`	string	No	`"item"`	Variable name for current item
`index`	string	No	`"index"`	Variable name for current index
`do`	string[]	Yes	-	Node IDs to execute each iteration
`concurrent`	boolean	No	`false`	Run iterations in parallel

* Must specify exactly one of: items, count, or while ** Required when using while mode

Loop Modes

Items Mode

Iterate over an array:

{
  "id": "send_emails",
  "type": "loop",
  "config": {
    "items": "{{users}}",
    "as": "user",
    "index": "i",
    "do": ["send_email"]
  }
}

Inside the loop, access:

{{user}} - Current array element
{{i}} - Current index (0-based)

Count Mode

Run a fixed number of times:

{
  "id": "retry_request",
  "type": "loop",
  "config": {
    "count": 3,
    "index": "attempt",
    "do": ["make_request", "check_success"]
  }
}

Count can be a template:

{
  "count": "{{request.body.quantity}}"
}

While Mode

Loop while a condition is true:

{
  "id": "paginate",
  "type": "loop",
  "config": {
    "while": "{{has_more_pages}} == true",
    "max": 100,
    "do": ["fetch_page", "check_more"]
  }
}

The max field is required to prevent infinite loops.

Output

{
  "iterations": 5,
  "results": [
    { "index": 0, "output": { ... } },
    { "index": 1, "output": { ... } },
    { "index": 2, "output": { ... } },
    { "index": 3, "output": { ... } },
    { "index": 4, "output": { ... } }
  ],
  "completed": true,
  "error": null
}

Field	Type	Description
`iterations`	number	Total iterations completed
`results`	array	Output from each iteration
`completed`	boolean	Whether loop finished normally
`error`	string	Error message if loop failed

Context Variables

During each iteration, these variables are available:

Variable	Description
`{{item}}` (or custom `as`)	Current item (items mode) or iteration number (count mode)
`{{index}}` (or custom name)	Zero-based iteration index

Example Access

{
  "id": "process_item",
  "type": "http",
  "config": {
    "method": "POST",
    "url": "https://api.example.com/items",
    "body": {
      "item_id": "{{order.id}}",
      "iteration": "{{i}}"
    }
  }
}

Examples

Process Array Items

{
  "id": "process_all_orders",
  "type": "loop",
  "config": {
    "items": "{{fetch_orders.output.body}}",
    "as": "order",
    "do": ["validate_order", "save_order"]
  }
}

Concurrent Processing

Process items in parallel for better performance:

{
  "id": "send_notifications",
  "type": "loop",
  "config": {
    "items": "{{subscribers}}",
    "as": "subscriber",
    "do": ["send_notification"],
    "concurrent": true
  }
}

Pagination Loop

Fetch all pages from a paginated API:

[
  {
    "id": "init_pagination",
    "type": "set",
    "config": {
      "key": "page",
      "value": 1
    }
  },
  {
    "id": "init_has_more",
    "type": "set",
    "config": {
      "key": "has_more",
      "value": true
    }
  },
  {
    "id": "fetch_all_pages",
    "type": "loop",
    "config": {
      "while": "{{has_more}} == true",
      "max": 50,
      "do": ["fetch_page", "update_pagination"]
    }
  }
]

Retry Pattern

Retry a request up to 3 times:

{
  "id": "retry_api_call",
  "type": "loop",
  "config": {
    "count": 3,
    "index": "attempt",
    "do": ["make_request", "check_if_should_retry"]
  }
}

Accessing Loop Results

After the loop, access results by index:

{
  "id": "summarize",
  "type": "transform",
  "config": {
    "output": {
      "total_processed": "{{process_all_orders.output.iterations}}",
      "first_result": "{{process_all_orders.output.results[0]}}",
      "all_results": "{{process_all_orders.output.results}}"
    }
  }
}

Nested Data Access

When iterating over objects with nested data:

{
  "id": "process_nested",
  "type": "loop",
  "config": {
    "items": "{{data.users}}",
    "as": "user",
    "do": ["process_user"]
  }
}

Inside process_user:

{{user.name}}           -> Access user's name
{{user.address.city}}   -> Access nested properties
{{index}}               -> Current iteration index

Performance Considerations

Use concurrent: true for independent operations
Set reasonable max for while loops to prevent runaway execution
Batch operations when possible instead of individual API calls
Limit iterations - very large loops can impact performance

Parallel Node - Run fixed branches concurrently
Transform Node - Process array data with pipes

Getting Started

Triggers

Nodes

Reference

Configuration

Config Fields

Loop Modes

Items Mode

Count Mode

While Mode

Output

Context Variables

Example Access

Examples

Process Array Items

Concurrent Processing

Retry Pattern

Accessing Loop Results

Nested Data Access

Performance Considerations

​Configuration

​Config Fields

​Loop Modes

​Items Mode

​Count Mode

​While Mode

​Output

​Context Variables

​Example Access

​Examples

​Process Array Items

​Concurrent Processing

​Pagination Loop

​Retry Pattern

​Accessing Loop Results

​Nested Data Access

​Performance Considerations

​Related

Configuration

Config Fields

Loop Modes

Items Mode

Count Mode

While Mode

Output

Context Variables

Example Access

Examples

Process Array Items

Concurrent Processing

Pagination Loop

Retry Pattern

Accessing Loop Results

Nested Data Access

Performance Considerations

Related