What format do the rename pairs use?

One pair per line, in the form oldName:newName, for example email:contact_email. List as many pairs as you need, one per line.

What happens if an oldName doesn't match any header cell?

The tool returns an error listing every unmatched name, rather than silently ignoring a typo and leaving that header unchanged.

Can I rename several columns at once?

Yes, list one oldName:newName pair per line and every matching header will be renamed in a single pass.

Does renaming affect any data rows?

No, only the header row (row 0) changes; every data row's values are completely untouched.

What if my desired new name itself contains a colon?

The tool splits on the first colon in each line, so a new name containing additional colons after the first one is preserved correctly.

Can I rename a column to the same name it already has?

Yes, that's allowed and simply leaves that header unchanged; it's not treated as an error.

CSV Column Renamer - Rename Header Columns

Overview

Introduction

Header names from an external export rarely match the naming convention your own tools or database expect, snake_case versus camelCase, abbreviations, inconsistent capitalization.

This tool renames as many header cells as you need in one pass, using a simple oldName:newName list.

What Is CSV Column Renamer?

A structural CSV tool that relabels one or more header cells based on a newline-separated list of oldName:newName pairs, leaving every data row's values completely untouched.

Every pair is matched against the header row by exact text; unmatched names are reported as an error rather than silently skipped.

How CSV Column Renamer Works

The rename list is parsed line by line, splitting each on its first colon into an old name and a new name, building a lookup map.

The CSV's header row is checked against that map: every old name must exist in the header, and the header row is rebuilt with matching cells replaced by their new names before re-serializing the CSV.

When To Use CSV Column Renamer

Use it when importing a CSV from an external source whose column names don't match your own schema's naming convention.

It's also handy for quickly clarifying a vague or abbreviated header (like "amt" to "amount") without opening a spreadsheet.

Often used alongside CSV Column Replacer, CSV Column Deleter and CSV Column Sorter.

Features

Advantages

Renames multiple columns in a single pass via a simple text list, no per-column UI needed.
Validates every old name against the actual header row, catching typos immediately instead of silently doing nothing.
Leaves data rows completely unaffected, this is purely a labeling change.

Limitations

Old names must match the header text exactly, including capitalization and whitespace.
There's no bulk pattern-based renaming (like a regex find-and-replace) across headers, each pair is a literal one-to-one mapping.

Examples

Renaming two columns at once

Input

id,amt,nm
1,120,Ada
2,90,Alan

Output

id,amount,name
1,120,Ada
2,90,Alan

With the pairs "amt:amount" and "nm:name", both header cells are relabeled; data rows are unchanged.

Best Practices & Notes

Best Practices

Copy the exact header text from your CSV's first row when writing the oldName side of each pair, to avoid an exact-match failure from a stray space or typo.
Rename ambiguous or inconsistent headers before running CSV Column Sorter, so the alphabetical order reflects your final, clear names.
Keep one pair per line even when renaming many columns, it's easier to review and edit than a single combined expression.

Developer Notes

Splits each non-empty line on its first `:` via `indexOf`, so a replacement name that itself contains a colon is preserved intact on the right-hand side; every old name is then checked for membership in the actual header array before any rename is applied, so a partial, silently-incomplete rename never happens.

CSV Column Renamer Use Cases

Normalizing an externally sourced CSV's headers to match your own naming convention before import
Clarifying abbreviated or vague header names for a shared or published CSV
Relabeling several columns at once as part of a larger CSV cleanup pass

Common Mistakes

Mistyping or mis-capitalizing an old header name, causing a not-found error instead of a silent no-op.
Expecting data values to change along with the header, renaming only relabels the header cell.

Tips

If you're unsure of the exact header text, extract it first with CSV Column Extractor or simply check the first line of your input.
Combine with CSV Column Sorter afterward to both clarify and alphabetize your CSV's columns in two quick steps.

CSV Column Renamer