Join two CSV tables by key

Choose a key column on each table. Duplicate key values can produce multiple output rows, just as they do in a relational join. Right-side name collisions are renamed instead of silently overwriting left columns.

Left CSV

Right CSV

Left key

Right key

Join type

ReadyBoth tables are parsed and joined in this browser tab.

Private browser-first tabular workflow

v10.78 connects viewing, editing, validation, cleanup, conversion, joining, reshaping and spreadsheet import/export around the established CSV/Excel tools. Text and supported workbook files are handled in browser memory; large files remain limited by device memory and browser rendering cost.

CSV and spreadsheet boundaries

CSV has no universal schema or type system. Delimiter detection and type summaries are practical heuristics, while repairs create a new copy instead of silently altering the source. Excel conversion focuses on cell values and simple worksheets rather than promising perfect preservation of formulas, macros, charts, external links, formatting or every workbook feature.

How to use this CSV Joiner

Join two CSV tables by matching key columns with inner, left, or full join behavior directly in the browser.

Enter, paste, upload, or choose the inputs shown in the tool above.
Adjust the available options for the result you need.
Review the output before copying, downloading, or using it elsewhere.

What this tool does

Paste or load two delimited tables, choose the key column on each side, preview matched rows, and export the joined CSV locally.

Practical tips and limits

Review the inputs and result before using the output elsewhere. Keep the original data when the operation changes or replaces content.