Local spreadsheet utilities

Merge Excel Files Online

Merge Excel files online when several small XLSX exports need one values-only workbook. Select multiple files in the order you want them processed. Put the first worksheet of each file into its own output sheet, or append the first-sheet records under a single shared header. This is a local assembly tool, not a comparison or deduplication service; it does not upload your workbook bytes.

Separate sheets are useful for keeping source exports apart. Sheet names come from filenames, with invalid characters replaced, names shortened to 31 characters, and case-insensitive collisions suffixed. Append mode requires identical first-row headers in the same order and rejects mismatches rather than guessing how to align columns. Only the first sheet from each input is included in either mode. Other sheets are intentionally excluded.

Try the merge excel files online tool

Ready. Input stays in your browser. Limit: 20 MB per file or pasted input.

How to merge Excel files

Choose at least two .xlsx files, each 20 MB or smaller. Files are processed in the order provided by the file picker.
Select Separate sheets or Append first-sheet rows. Check that append headers match exactly.
Select Merge to XLSX to build a new workbook from cell values.
Download merged.xlsx and review the result before replacing any source files.

Example input and output

File A first sheet: id | amount; 1 | 20
File B first sheet: id | amount; 2 | 30
Append output: id | amount; 1 | 20; 2 | 30

Data rules and limits

No rows are deduplicated, sorted, or matched by ID. Empty rows inside the used range are retained. In append mode, the header is written once; separate-sheet mode retains each first sheet’s header. Work on copies and keep the original files for any later formula or formatting review.

Inputs are limited to 20 MB each, matching WorkbookDiff’s file-validation limit. Large files can expand substantially in memory; use smaller inputs if your browser slows down. Excel output must fit worksheet row and column limits. Formatting, formulas, and charts may not be preserved: these tools write values, not a full-fidelity workbook copy.

Need to verify versions instead? Compare two Excel files. For a documented review, see the one-time audit handoff report; conversion, merging, and splitting do not generate an audit report.

Frequently asked questions

Can I merge CSV or old XLS files?

No. Merge accepts .xlsx only, with a 20 MB limit per input file. Legacy .xls, .xlsm, CSV, and encrypted workbooks are not supported. Multiple files and expanded data can consume substantially more browser memory.

Are formatting, formulas, and charts preserved?

No. The output writes values only. Formatting, formulas, and charts may not be preserved. Formulas use cached results when present and are not recalculated; missing cached results become blank cells.

Which sheets are merged?

Only the first worksheet of each input file is used. Separate-sheet mode creates one output sheet per file, while append mode combines the first sheets and keeps the shared header once.

Are files uploaded?

No workbook bytes are uploaded. Merging and XLSX creation run in browser memory. Keep source copies and use the comparison tool separately if you need to review version differences.

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