CSV Column Mapper

How to use this developer tool

1. Paste the CSV input or load a local file.
2. Choose the options that match the source format.
3. Select Map Columns or press Ctrl/Cmd + Enter.
4. Review the summary and export the output you need.

What this developer tool does

This page applies an ordered output-name to source-name mapping and serializes the selected columns as valid CSV. The main output is ready to copy, while the structured exports retain the diagnostic fields used in the summary.

This mapper handles column selection and renaming, not calculated fields or row-level transformations.

Example

Input

id,first_name,last_name,email
1,Ada,Lovelace,ada@example.com
2,Lin,Chen,lin@example.com

--- MAP ---
user_id=id
email=email
first=first_name
last=last_name

Running the sample produces a tool-specific report in the output panel, with counts that correspond to the parsed records or nodes.

Use cases

• Check incoming CSV before an import or migration.
• Create repeatable fixtures for parser and ETL tests.
• Inspect structure without installing a command-line package.
• Export a compact report for code review or issue tracking.

Tips for reliable output

• Keep an untouched copy of the source before transforming it.
• Test one representative edge case as well as the happy path.
• Review quoted fields, Unicode, and empty values explicitly.
• Use the JSON export when another program will consume the report.
• Re-run the tool after changing any parsing option.

Processing details

Each mapping line uses output_header=source_header. Source names must match exactly; repeating a source duplicates it and omitted sources are dropped. Processing time is measured in the browser and the original input is left unchanged.

This mapper handles column selection and renaming, not calculated fields or row-level transformations.