About the TSV Column Adder
A TSV file keeps each field apart with a tab character, and it is what you get when you copy cells out of a spreadsheet. This tool adds one more column to such a table. Paste the tab-separated text, say where the new column should sit, give it a heading and choose how it is filled: with numbers that count up, or with one fixed piece of text in every row. Because the separator is fixed to the tab, commas inside your cells cause no confusion. The result can be pasted straight back into a spreadsheet. Everything is done in your browser.
Updated October 2026
How to use the TSV Column Adder
- 1Paste your TSV, or cells copied from a spreadsheet, into the left box.
- 2Type the position of the new column; 1 is the front and the word last adds it at the end.
- 3Type a heading for the column, or untick the header option if the table has none.
- 4Choose counting numbers or the same text in every row.
- 5Copy the new table or download it as a .tsv file.
Why tab-separated data is handy
Tabs almost never appear inside real data, so a tab-separated table needs no quoting rules, unlike comma-separated data where every comma in a name or address needs protecting. That is why spreadsheets, databases and many science tools use TSV for copying and exporting tables.
Adding a column to a TSV in a spreadsheet is easy for a small table, but for a large export a text tool is faster and leaves other cells exactly as they were.
Position and fill
Position 1 puts the new column before everything else. A larger number puts it after that many columns, and last puts it at the right edge. Counting numbers suit IDs and sort keys. Fixed text suits a label such as a source, a status or a month.
If every row needs its own different value, fill the column here with numbers and merge the real values later in your spreadsheet.
- Front: 1
- After the first column: 2
- End: last
Before you import
Look at the first few rows of the result and compare them with the sample file of the system that will read it. If the importer wants a header row, keep the header option ticked and give the column the exact name it expects. If your data is comma separated, use CSV Column Adder in the same way. TSV Column Extractor pulls out a single column to check, and TSV to CSV Converter changes the file once you are done.
Features
- Works on tab-separated text only
- Insert at any position or at the end
- Counting numbers from any start value
- Same text in every row
- Commas inside cells are left alone
- Private: nothing is uploaded
Frequently asked questions
How do I add a column to a TSV file?
Paste the tab-separated text, set the position and heading of the new column and choose how to fill it. The new table appears on the right, still separated by tabs.
Why use a TSV tool instead of a CSV tool?
Because the tab is fixed as the separator, a cell such as Smith, John with a comma in it is never split. A general tool that guesses the separator can be fooled by commas in the data.
Can I paste directly from Excel or Google Sheets?
Yes. Cells copied from a spreadsheet arrive as tab-separated text, so you can paste them as they are and paste the result back.
How do I add a running number to every row?
Choose counting numbers as the fill and set the first number. With 1 the rows get 1, 2, 3 and so on, and the heading row, if you keep it, gets the column name.
What if my table has no heading row?
Untick the option that says the first row holds column names. Every line is then treated as data and the new column is filled on every line.
Is my table uploaded?
No. The column is added by code in your browser tab, and nothing is sent to a server.