// remap column names in bulk — no upload needed
Rename and remap CSV column headers in bulk using find-and-replace mapping rules. Fast, browser-based, no upload required.
OldName => NewName · Lines starting with // are comments
Ready to remap
Paste CSV + mapping rules, then click Rename ColumnsDrop any CSV into the input box — commas, semicolons, tabs, and pipes are auto-detected.
Enter one rule per line in the format OldName => NewName. Skip columns you don't want to rename.
Click Rename Columns — preview the diff, then copy or download your renamed CSV file.
The CSV Column Renamer lets you rename CSV headers in bulk using simple find-and-replace mapping rules. No scripting or spreadsheet formulas required — just paste your CSV, define your rules, and get clean output instantly.
The tool automatically detects commas (,), semicolons (;), tabs, and pipes (|) — whichever appears most frequently in the first row is used as the delimiter for the entire file.
Columns without a matching mapping rule are left unchanged. Only headers that exactly match a rule's left-hand side (OldName) will be renamed — the rest pass through untouched.
Yes. The matching is case-sensitive: email and Email are treated as different column names. Make sure your rule's left-hand side exactly matches the header in your CSV.
No. Only the first (header) row is affected by the rename rules. All data rows are preserved exactly as they appear in your original CSV — no values are changed.
Yes! Any line that starts with // is treated as a comment and ignored during processing. This helps you annotate or temporarily disable rules without deleting them.
No. All processing happens locally in your browser via a JavaScript API call on the same page. Your data never leaves your machine and is not stored anywhere.
A CSV Column Renamer is a tool that lets you rename the header columns of a CSV file in bulk, using simple mapping rules you define. Instead of opening a spreadsheet editor, manually clicking each column header, and typing a new name — you can define all your rename rules in one place and apply them to hundreds of columns at once.
Whether you're a developer cleaning up API exports, a data analyst standardizing field names before database import, or a team lead enforcing consistent naming conventions, a bulk CSV column renamer saves significant time and eliminates human error.
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CSV files come from many different sources — databases, APIs, SaaS exports, spreadsheets — and each source tends to use its own naming conventions. A CRM might export first_name, while your analytics platform expects FirstName, and your warehouse uses customer_first. Before you can load the data into the right destination, you need to remap those headers.
Doing this manually in Excel or Google Sheets works for a handful of columns, but falls apart quickly when you have 30, 50, or 100+ fields. A column renamer lets you define the full mapping once, apply it in seconds, and reuse the same ruleset next time you get a similar export.
The mapping syntax is intentionally simple: one rule per line, using the format OldName => NewName. The left side is the exact header string as it appears in your CSV (case-sensitive). The right side is the new name you want. Any column that doesn't have a matching rule is left exactly as-is.
You can also add comment lines starting with // to annotate your ruleset or temporarily disable a rule without deleting it. This makes the mapping file easy to version-control and share with teammates.
CSV is short for "comma-separated values," but in practice many CSV files use semicolons (common in European locales), tabs (TSV files), or pipes. This tool automatically detects the delimiter by scanning the first row and picking the character that appears most frequently — so you don't have to configure anything. Comma, semicolon, tab, and pipe are all supported out of the box.
All processing happens client-side in your browser. Your CSV data is never uploaded to any external server, logged, or stored. This matters when working with sensitive or proprietary data: customer lists, internal pricing tables, HR records, or financial exports that you wouldn't want to paste into an unknown web service.
Here are some of the most frequent scenarios where a CSV column renamer proves invaluable:
This tool specifically renames column headers — it changes the name of a column without touching the data or changing its position. If you also need to reorder columns, extract a subset of columns, or sort rows, check out the related tools below: CSV Column Extractor lets you pick which columns to keep and in what order.
A few habits that make your mapping rulesets more maintainable over time: group related renames together with comment headers (e.g. // User fields), keep the file under version control alongside the scripts that consume the CSV, and name your rules files descriptively (e.g. crm-to-warehouse.map). Since the format is plain text, it integrates naturally with Git, code reviews, and documentation.
Also remember that matching is exact and case-sensitive. If your CSV has a column called Email Address (with a capital E and a space), your rule must say Email Address => email — not email address => email. Use the header diff preview to confirm that each rule matched correctly before downloading.