Loop Block

Container block that executes child workflow blocks in a loop. Supports both count-based loops (for) and collection-based loops (forEach). Child blocks placed inside the loop container will be executed for each iteration — reach for it whenever you need to process a list of items or repeat an action a fixed number of times.

Overview

When to Use

• Process every item in an array (emails, records, API results) with a forEach loop
• Repeat an action a fixed number of times with a count-based for loop
• Batch-send messages or notifications to multiple recipients
• Iterate over pages of API results one at a time
• Run a sub-workflow step for each element in a structured output from an Agent block
• Apply a transformation or enrichment to each row in a data collection

Configuration

Loop Type

A dropdown that selects the iteration strategy. Required to determine which additional fields appear.

Iterations

A short-input field (id: count) that specifies how many times the loop should run. Only shown when Loop Type is for.

• Placeholder: 5
• Required when loopType = for

Collection Items

A long-input field (id: collection) for the array or object to iterate over. Only shown when Loop Type is forEach.

• Placeholder: ['item1', 'item2', 'item3'] or {{previous_block.output}}
• Description: Array or object to iterate over. Use {{block_id.output}} to reference other blocks.
• Required when loopType = forEach

Max Iterations

A slider (id: maxIterations) that sets a safety ceiling on the number of iterations to prevent runaway loops.

• Range: 1 – 100
• Description: Safety limit to prevent infinite loops

Parallel Execution

A switch (id: parallelExecution) that controls whether iterations run concurrently.

• Description: Execute iterations in parallel (faster but uses more resources)

Stop on Error

A switch (id: stopOnError) that controls whether a failing iteration halts the entire loop.

• Description: Stop loop execution if any iteration fails

Inputs & Outputs

Inputs:

• collection (json) — Collection of items to iterate over (for forEach loops)
• count (number) — Number of iterations (for count-based loops)

Outputs:

• iterations (number) — Total number of iterations completed
• results (json) — Array of results from each iteration
• executionTime (number) — Total execution time in milliseconds
• status (string) — Loop execution status (completed, error, or cancelled)
• currentIteration (number) — Current iteration number (available during execution)
• currentItem (json) — Current item being processed (for forEach loops, available during execution)

Tools

This block has no external tool integrations. It is a container block handled directly by the loop executor — no tools.access entries are needed.

YAML Example

loop_1:
  type: loop
  name: "Loop"
  inputs:
    loopType: "forEach"
    collection: "{{api_fetch_1.response.items}}"
    maxIterations: 50
    parallelExecution: false
    stopOnError: true
  connections:
    outgoing:
      - target: next-block-id