CSV Join by Key

Left-join two CSV datasets using a unique key field.

01 / INPUT DATA

Data workbench

Local processing

Select two CSV files and enter a join key that appears in both. Duplicate right-hand keys are refused.

Choose a local file Or paste text below.

Input text

Setting

Additional setting

Guard exported CSV against spreadsheet formulas (recommended)

Ready. Your files are not uploaded.

02 / RESULTS

Your output

Preview (up to 30,000 characters)

Some diagnostic tools produce reports rather than a modified file. Always review exported data before using it.

USE IT SAFELY

Before you export

Keep an untouched source copy, verify row counts and important identifiers, and open a few exported records in your target application. This tool cannot reconstruct information already lost from the source file.

FORMAT SUPPORT

Know the boundaries

UTF-8 CSV, TSV, JSON, JSONL and text are supported. Selected XLSX worksheets can be inspected/exported using cached values; original workbook formatting, macros, charts and formulas are not preserved. XLS binary files remain unsupported.

Read XLSX compatibility limits →