ConvertCSV

Browser-based CSV transform

Add CSV Column

Add a new column with the same value on every row, at any position. Everything runs locally in your browser — paste CSV, set options, preview, then copy or download.

Input

Paste CSV or upload a file

Options

Configure how this transform runs

Output Preview

Transformed CSV

Run the transform to preview CSV output here.

Add CSV Column

Sometimes a batch of rows needs a label that the source file never carried: the region a file came from, the export date, or a status flag that tells rows apart after a merge. Add CSV Column writes one new header and the identical value into every data row. You choose the header name, the value, and the position it occupies.

Every row receives the same text, which suits tagging and batching rather than calculating. It can insert a column at the front, somewhere in the middle, or at the end.

Key features

  • One constant value written to every data row
  • Position from the first column to the end, with append as the default
  • Blank value allowed for placeholder columns
  • Duplicate-name check that ignores letter case

About the CSV to CSV with an added column format

The new header is placed at the position you enter, where 1 is the leftmost column. A blank position appends it at the end. The value may be empty, which gives a column of blanks that someone can fill in later. Existing columns keep their names, their order, and their cell contents.

Header names are compared without regard to letter case, so Region cannot be added beside region. The position must be a whole number from 1 up to one more than the current column count.

How it works

The tool validates the name and the position, splices the new header into the header list at the chosen index, and writes the same value into each record under that header before generating the output.

Common use cases

  • Stamping every row of a regional export with its source before combining several regions.
  • Adding a quarter label to rows from one sheet so they remain identifiable after a merge.
  • Creating an empty reviewed column that a team fills in by hand after the file is returned.
  • Tagging rows with an import batch ID so a bad load can be located and removed later.

How to use this tool

  1. Provide the CSV, pasted or uploaded, with a header row.
  2. Enter the new header and the constant that every row will receive.
  3. Set a position if the column belongs away from the end; 1 is the leftmost.
  4. Confirm the new header sits where you expect in the preview, then download.

Example

Input (two rows)

name,city
Ada,London
Grace,Arlington

Output with source = crm-export at position 1

source,name,city
crm-export,Ada,London
crm-export,Grace,Arlington

Tips for best results

  • Add the source column before Merge CSV. The stacked result then keeps a clear marker on every row that came from each file.
  • Place the tag next to the key column so it is visible alongside the identifier when the file is opened in a spreadsheet.
  • Leave the value blank when the column exists only as a workspace for later annotations.

Common errors and how to fix them

A column named "CITY" already exists.
The name is already in the header row, even with different capitalization. Choose a name that does not appear in the file.
Position must be a whole number from 1 to 3.
The message gives the valid range for your file: a two-column file accepts 1 to 3, where 3 is the end. Enter a whole number inside it, or clear the box to append.
Enter a name for the new column.
The name box was empty or held only spaces. A header needs at least one visible character.

Frequently asked questions

Can the value be a formula or a timestamp that updates?

No. The text in the value box is written as typed on every row. Use a spreadsheet when you need formulas or changing values.

Can several columns be added in one run?

Not in a single run. Feed the output back in and add the next column with its own name, value, and position.

For more background on data formats and conversion workflows, read our format guides.