Control Flow
Loop and Batch Processing Documentation
Iterate over lists of files or data rows to perform high-volume document automation.
Quick Answer: What is the Loop Node?
[!NOTE] The Loop Node (and its batch variants) allow you to repeat a sequence of actions for every item in a list. If you have 100 PDFs to convert, the Loop Node ensures the workflow runs 100 times—once for each file—automating what would otherwise be a tedious manual task.
Core Capabilities
1. Mass Conversion
Upload a folder of 50 images to a File Input Node. Connect a Loop Node followed by an Image Convert Node. The workflow will walk through each image and convert it, producing a final list of 50 converted files.
2. Record-by-Record Automation
Use a Spreadsheet Node to pull customer data. The Loop Node will iterate through each row, generate a personalized letter via Document Generation, and email it to the customer.
3. Nested Workflows (Advanced)
A loop can trigger a Sub-Workflow for each item, allowing you to build extremely complex modular architectures where each loop iteration is itself a multi-step process.
Configuration Guide
| Field | Setting | Impact |
|---|---|---|
| Input Source | The Array to Loop | Determines what data to iterate over (e.g., {{excel_1.rows}}). |
| Concurrency | Serial vs. Parallel | Serial is safer for API limits; Parallel is 10x faster for CPU tasks. |
| Max Iterations | Safety Limit | Prevents infinite loops or excessive credit consumption. |
Best Practices
- Keep it Lean: Only put the nodes that need to repeat inside the loop. Triggers and aggregators should stay outside the loop boundaries.
- Aggregation: Use a Wait or Merge Node after the loop if you need to zip all the loop's output files into a single download.
[!TIP] Processing millions of rows? Split your data into smaller spreadsheet chunks (e.g., 500 rows each) to ensure the browser's memory remains stable during the loop.