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Excel & CSV

Join CSV files by key

Join two CSV files using matching ID columns. Choose an inner, left or full outer join and download unmatched rows separately.

Drag and drop files here

CSV

Up to 2 files · 5 MB per file

Use a direct public file link up to 20 MB, or the smaller limit shown above. The download service retrieves the file; sign-in links are not supported.

    Download an example file · Download a second example file

    Join CSV files by key

    Combine customer, product or inventory exports by ID instead of row position. Choose a key column in each file, even when the names differ. Output headers use left. and right. prefixes; match_status distinguishes absent rows from blank cells. Imported formula-like values are escaped for spreadsheet safety.

    How to use this tool

    1. Upload the left CSV, then the right CSV. Use the arrow buttons to swap their roles.
    2. Enter the exact key column names and choose which rows to keep.
    3. Download the joined CSV, unmatched rows and summary. Check the match_status column before using the data.

    Supported input formats

    • CSV

    Available settings

    • Left key column
    • Right key column
    • Rows to keepLeft join: all left rowsInner join: matching rows onlyFull outer join: all rows
    • Key matchingExact matchTrim spacesTrim spaces and ignore case

    Output and limitations

    Join two CSV files using matching ID columns. Choose an inner, left or full outer join and download unmatched rows separately.

    First file: left. Second file: right. Comma-separated UTF-8 CSV, up to 5 MB, 10,000 rows and 100 columns per file. Keys must be unique and non-empty. Export Excel sheets as CSV first.

    What happens when a key appears more than once?

    The join stops so duplicate keys cannot silently multiply rows. Remove duplicates or create a unique combined key first. Matching ignores spaces or case only when you choose that option.

    What if processing fails?

    Check the supported formats and file limits, then try a smaller file. Keep an original copy. A clear error message will explain an unsupported input or an unavailable processing service.

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