Prepend a CSV Column
Quickly prepend columns at the beginning of a CSV file. Runs entirely in your browser, so your data never leaves your device.
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Output
The result appears here as you type.
How to use Prepend a CSV Column
- 1. Paste the CSV. Enter the existing rows in the input pane. The tool will push a fresh column in front of the current first column on every line, keeping all existing values in their rows.
- 2. Name the new column and set a fill. Column name becomes the heading in the header row. 'Fill value for data rows' is written into every data cell; leave it blank for empty cells you plan to populate later.
- 3. Mark the header row. Check First row is header so the first line receives the column name while all remaining lines get the fill value. Uncheck it and every line, including the first, is treated as data.
- 4. Copy the widened CSV. Copy the result from the output pane. The new column sits at position one on every row, ready for ids, flags or timestamps before the file moves on to its importer.
When to use Prepend a CSV Column
Prepend a CSV Column adds a new first column across an entire file in one pass. Import schemas often demand an id, source or status column in the leading position, and adding one by hand in a spreadsheet means inserting, naming and filling separately. Here it is a single operation on plain text.
- Adding an id column an importer requires. A bulk-upload template insists the first column is id, even if empty. Prepend an id column with a blank fill and the file passes the schema check without renumbering anything.
- Tagging rows with their source. You are about to merge exports from three regional systems. Prepend a source column filled with eu, us or apac to each file first, so provenance survives the merge.
- Stamping a batch date. Nightly files get concatenated into a history table. Prepending a batch_date column filled with today's date lets downstream queries separate loads without relying on file names.
Examples
Add an id column in front
Input
name,age Ada,36
Output
id,name,age ,Ada,36
About the Prepend a CSV Column tool
Prepend a CSV Column does its work locally, right in the browser. Quickly prepend columns at the beginning of a CSV file. There is no upload step, no queue and no account, and your data never travels over the network.
It belongs to the CSV Tools collection on EditSafely, a set of 133 small, focused CSV utilities that share the same instant, private workspace.
You can shape the output with 3 settings, including Column name, Fill value for data rows and First row is header, and the result refreshes the moment you change one. A worked example further down the page shows exactly what the tool produces for a real input.
Running locally also makes the tool fast and dependable: results appear as you type or drop a file, there is no server outage that can take it down mid-task, and confidential data can be processed without a second thought.
Frequently asked questions
Is Prepend a CSV Column free to use?
Yes, it is completely free. All 2,658 tools on EditSafely work without an account, a subscription or usage limits.
Is it safe to paste sensitive or confidential data?
Everything happens locally. Your browser downloads the tool's code once, then does all the processing itself; nothing you enter is transmitted, stored or logged. You can even go offline after the page loads and it will still work.
How much text can I process at once?
There is no fixed limit. Because the work happens on your own device rather than on a shared server, the practical ceiling is your machine's memory, which comfortably handles inputs far larger than typical online tools allow.
Do I need to sign up or install anything?
No. The tool works in any modern browser on desktop, tablet or phone. There is no account to create, no extension to add and no software to install.
How do I use the result?
The output panel has a one-click copy button, and you can keep refining the input while you work; the result updates in place as you type.