UseFreeTools

Dataset Column Mapper

Map source columns to an explicit target schema and export a reordered CSV with a reusable mapping profile.

Files stay on your device No sign-up Free to use
How this works

The tool runs in this browser. Your file or text is not uploaded to UseFreeTools. Check this tool's limits for anything it may save on your device.

Privacy details

Showing an example. Edit to see your own.

CSV or TSV with distinct headings. Clear this box to choose a file.

Ordered columns, each with name and required. Optional default strings fill unmapped columns; they do not replace blank mapped cells.

Map target names to exact source headings. Unknown, duplicate and missing required mappings are refused. Unmapped source columns are listed and left out.

Drop your CSV file here

or choose one from your device

One UTF-8 file, up to 20 MiB. Up to 100,000 rows, 500 columns and 2,000,000 cells.

    Adds an apostrophe before cells that a spreadsheet may run as a formula. This changes those exported values; turn off only for a trusted import that needs raw text.

    Processed in your browser. Your inputs stay on this device.

    How to use Dataset Column Mapper

    1. Load the source table and enter target columns.
    2. Define explicit source-to-target mappings, including required fields.
    3. Review the mapped result and export the CSV and profile.

    Example: Dataset Column Mapper

    Rename two source headings.

    You add
    CSV: first,last Ada,Lovelace. Schema: {"columns":[{"name":"given_name","required":true},{"name":"family_name","required":true}]}. Mapping: {"given_name":"first","family_name":"last"}.
    You get
    The CSV headings become given_name,family_name and the single row remains Ada,Lovelace.

    Options

    Target schema
    The ordered columns array defines output headings. Optional default strings fill unmapped target columns, not blank values in mapped source cells.
    Mapping
    Map target names to exact source headings. Missing required mappings, unknown names and duplicate use prohibited by the supported contract are refused. Unmapped source columns are left out.
    Formula protection
    Exported cells that a spreadsheet might evaluate receive a protective apostrophe. This changes text values; choose the setting deliberately for the destination import.

    Supported inputs and limits

    Explicit mapping, with no semantic guessing or automatic required-field filling. Duplicate headers, unknown columns and missing required mappings are refused. Export formula protection can change cells and is disclosed in the result. Up to 20 MiB, 100,000 source rows, 500 source columns, 100 target columns and 2,000,000 cells. Preview shows at most 100 rows. Optional unmapped columns may use an explicitly supplied default; required targets cannot. Profiles do not contain source records.

    Where your input is processed

    This tool processes your input in this browser. Your text and files are not uploaded to UseFreeTools. Check this tool's limits for anything it may save on your device.

    Mapping changes structure without finding missing data

    The tool reorders and names supplied columns according to your schema. It does not guess a match from similar names, combine values or replace a blank mapped cell with a default. Review the excluded-source report before relying on the result as a complete export.

    Keep the schema with the import recipe

    A target system can impose types, unique keys or validation that this text mapper does not check. Retain the schema, mapping and delimiter choices with the source file, then test a small output in the destination application.

    Questions about Dataset Column Mapper

    Will similar header names be matched automatically?

    No. You choose mappings so a similar name cannot silently send values to the wrong destination.

    What is saved in a profile?

    The schema and mapping needed to repeat the transformation. Inspect the profile before sharing it; it can include your header names.

    Why can an exported cell gain an apostrophe?

    Spreadsheet formula protection prefixes dangerous formula-like text. The result reports this modification.

    Project manager: Tony Hines · Content updated 4 October 2026 · Report a problem

    Related tools

    All tools in Data and Spreadsheets

    CSV Viewer

    Filter, sort and export matching CSV rows.