Insert CSV Columns
Add columns at a chosen position in a CSV file or pasted dataset, fill their values, and download the updated CSV without uploading your data.
UTF-8 CSV or plain text up to 10 MB. Processing happens locally in your browser.
Comma-separated names, in insertion order.
One value for each new column.
Use 1 for the first column. Leave blank to append at the end.
A QUICK WALKTHROUGH
How to use this tool
- Choose a CSV file or paste comma-separated text into the editor.
- Enter matching column names and default values, then choose where the new columns should be inserted.
- Insert the columns, review the preview, and download the updated CSV.
Insert several columns together
Enter column names and default values as comma-separated lists. Each name is paired with the value at the same position, so you can add multiple fields in one operation.
Rows and quoted fields stay structured
The parser handles commas inside double-quoted fields, escaped double quotes, and line breaks inside quoted fields. Existing rows are preserved; shorter rows receive the inserted values at the selected position.
Local processing with a practical limit
Reading, parsing, previewing, and downloading happen in your browser. Input files are limited to 10 MB, and the preview is limited to 100,000 characters for responsiveness. The tool expects comma-separated UTF-8 text.
GOOD TO KNOW
Common questions
How do I add multiple columns?
Enter the new header names separated by commas, then enter the same number of default values separated by commas. Quoted values can contain commas.
Where can the new columns be inserted?
Choose the first existing column before which to insert them, or choose the end to append them after the current fields.
Are existing CSV values uploaded?
No. The file is read and transformed locally in your browser.
Does this detect semicolon-separated data?
No. This page uses commas as the delimiter. Convert another delimiter to CSV first.