Tutorial: Process Multiple Files via Form - Binary Data & Loops

This workflow demonstrates how to handle multiple file uploads using n8n's Form Trigger node, where users can select and submit multiple JSON files (configurable for other types). The files arrive as binary data in a single 'files' field. The Split Out node then extracts each file into separate items, preserving binary data, making it ready for batch processing.

Next, a Split In Batches node (Loop Over Items) iterates over the split items using $runIndex to track each file dynamically. The Read/Write File node saves each file with a unique name like 'out_{filename}{runIndex}', showcasing correct access to binary data via expressions like 'files{{$runIndex}}'. This pattern is crucial for workflows involving file processing, such as sending batches to AI APIs for analysis or bulk data imports.

Benefits include mastering tricky n8n concepts like binary data manipulation, looping with $runIndex, and Split Out/In nodes, saving hours of trial-and-error for developers. Use cases: batch file validation, AI document processing pipelines, automated backups from forms, or integrating with tools like OpenAI for multi-file analysis. Easily adaptable by swapping the Save node for HTTP Request to POST files elsewhere.