Add a Row Index, UUID, or Key Column to CSV

Paste CSV, then insert a generated key column: row numbers, UUIDs, or composite values built from existing columns. Runs in your browser.

CSV dataGenerated valueNew column nameInsert positionReference column (for before/after)First row is a headerStart numberStepZero-pad width

PrefixSuffixComposite source columnsComposite separatorUUID versionUUID formatDelimiter

Try:

Updated CSV

About this tool

Add a generated key column to CSV or delimiter-separated data without leaving your browser. Use it for spreadsheet imports, test fixtures, database seeds, invoices, exports that need stable row IDs, or quick QA matrices.

The default mode adds a leading index column starting at 1:

name,city
Ada,London
Lin,Taipei

becomes:

index,name,city
1,Ada,London
2,Lin,Taipei

You can also build zero-padded values such as INV-0001, add one UUID per row, or create a composite key from existing columns like region-dept. Delimiters can be auto-detected or fixed to comma, tab, semicolon, or pipe, and quoted CSV fields are parsed with normal RFC 4180 double-quote rules.

Limits and edge cases

Input is capped at 5,000,000 bytes to keep browser runs responsive.
has_header is on by default. Turn it off for headerless CSV so every row gets a generated value.
position = before or after needs reference_column, which can be a header name or a 1-based column number.
Composite mode needs columns, a comma-separated list of source columns by header name or 1-based number.
UUID v4 values are random. UUID v7 values are time-ordered for the current run.
The output preserves the chosen delimiter, but CSV quoting may be normalized by the CSV writer.

FAQ

Can I start counting at zero instead of one?

Yes. Set Start number to 0. You can also change Step to count by 5s, count down with a negative step, or combine it with Zero-pad width for IDs like 0000, 0001, 0002.

How do I add IDs at the end of the CSV instead of the first column?

Set Insert position to End. To place the new column near an existing field, choose Before reference column or After reference column, then enter a header name such as email or a 1-based column number such as 3.

What is composite mode for?

Composite mode joins values from existing columns into a business key. For example, with columns region,dept, rows like EU,ops and US,eng become keys EU-ops and US-eng. Change Composite separator if you need EU::ops or another format.

What UUID formats are available?

UUID mode can emit standard lowercase UUIDs with hyphens, uppercase UUIDs, compact UUIDs with no hyphens, {braced} UUIDs, or urn:uuid: strings. Choose v4 for random IDs or v7 for IDs that sort in row order for the current run.

Developer & Automation Access

Run it from the terminal

Same engine as this page, headless — via the gizza CLI:

gizza tool csv-row-index-adder "name,city
Ada,London
Lin,Taipei"

New to the CLI? Get gizza →

Open it by URL

Pre-fill and auto-run this tool with query parameters — the names match the API/CLI:

https://gizza.ai/tools/csv-row-index-adder/?data=name%2Ccity%0AAda%2CLondon%0ALin%2CTaipei&mode=sequential&column_name=index&position=start&reference_column=city%20or%202&has_header=true&start=1&step=1&pad_width=0&prefix=INV-&suffix=-2026&columns=region%2Cdept%20or%201%2C2&separator=-&uuid_version=4&uuid_format=standard&delimiter=auto

Machine-readable descriptor: tool.json — title + parameters JSON Schema for agents.