Append CSV Files or Join Tables by Key.
DataOlllo combines data locally: append rows when exports share the same structure, or join tables when they share an identifier. Read the large CSV merge workflow before choosing your operation.
Download Data MergerDownloads standard DataOlllo PC AppStop Copy-Pasting Across 50 Files
Illustrative append result. Before merging, compare headers and data types. After a join, check unmatched keys and repeated IDs, which can multiply output rows.
Master Your Datasets
Folder Batch Merge
Just point to a folder containing hundreds of CSVs. DataOlllo reads and appends them into one dataset that you can inspect with the large CSV viewer.
Auto Column Alignment
Different standard headers across files? DataOlllo auto-aligns columns intelligently even if they are in different orders.
Flexible Joins
Need to join instead of append? Perform Left, Right, Inner, or Outer joins via matching keys with no SQL required.
Your data is yours. Keep it that way.
Standard file merging runs locally on your machine.
Optional online AI features are separate. Review the privacy policy before working with sensitive exports.