Insert CSV Columns

What It Does

Add new empty or pre-filled columns to your CSV data at any position. Insert one or multiple columns between existing ones, at the beginning, or at the end of your dataset.

How It Works

Insert CSV Columns applies a focused transformation to the input so you can compare the before and after without writing a custom script for a one-off task.

Unexpected output usually comes from one of three places: the wrong unit of transformation, hidden formatting in the source, or an option that changes the rule being applied.

All processing happens in your browser, so your input stays on your device during the transformation.

Common Use Cases

• Add a status column to track processing state in a workflow
• Insert an index or row number column at the beginning
• Add placeholder columns to match a required import template
• Create a notes column for manual annotations alongside existing data
• Insert calculated or derived columns with default values

How to Use

1. Paste your CSV data into the input area.
2. Specify the position for the new column (before or after a given column).
3. Enter a header name for the new column.
4. Optionally provide a default value for all rows.
5. Click Insert and copy the result.

Features

• Insert at any position: beginning, end, or between columns
• Set custom header names for new columns
• Fill with a default value or leave empty
• Insert multiple columns at once
• Preserves all existing data

Examples

Below is a representative input and output so you can see the transformation clearly.

name,age,city
Ada,36,London
Lin,29,Berlin

name,role,age,city
Ada,admin,36,London
Lin,editor,29,Berlin

Edge Cases

• Very large inputs can still stress the browser, especially when the tool is working across many columns. Split huge jobs into smaller batches if the page becomes sluggish.
• Empty or whitespace-only input is technically valid but may produce unchanged output, which can look like a failure at first glance.
• If the output looks wrong, compare the exact input and option values first, because Insert CSV Columns should be repeatable with the same settings.

Troubleshooting

• Unexpected output often means the input is being split or interpreted at the wrong unit. For Insert CSV Columns, that unit is usually columns.
• If a previous run looked different, check for hidden whitespace, changed separators, or a setting that was toggled accidentally.
• If nothing changes, confirm that the input actually contains the pattern or structure this tool operates on.
• If the page feels slow, reduce the input size and test a smaller sample first.

Tips

When inserting columns to match a template, insert them in reverse order from right to left — this way each insertion does not shift the positions of columns you still need to add.