Excel Merge & Duplicate Checker
Merge multiple Excel files into one and automatically detect duplicate rows with color coding. Perfect for consolidating orders, surveys, and reports. 100% browser-based.
About This Tool
Excel Merge combines multiple Excel (XLSX) files or sheets into a single unified spreadsheet. Merge by appending rows, combining matching columns, or consolidating multiple sheets — perfect for HR teams merging employee data, analysts combining monthly reports, and anyone unifying scattered spreadsheet data.
Drag & drop Excel files here, or click to browse
.xlsx, .xls, .csv (max 20 files, 50MB each)
What is Excel Merge & Duplicate Checker?
Excel Merge & Duplicate Checker is a free online tool that combines multiple Excel files (.xlsx, .xls, .csv) into one and automatically detects duplicate data rows.
Use cases: Consolidating purchase orders, combining order data, merging vendor reports, aggregating survey results, unifying monthly sales data, and more.
All processing happens in your browser, so you can safely handle files containing personal or sensitive data without worrying about privacy.
How to Use
- Upload your Excel files (.xlsx, .xls, .csv) by dragging or clicking.
- Adjust merge mode, header handling, and duplicate detection settings.
- Click 'Merge' to combine files and automatically detect duplicates.
- Review the preview, then download the result as .xlsx or .csv.
Frequently Asked Questions
Are my files uploaded to a server?
No, all processing happens entirely in your browser. Your files are never sent to any server, making it 100% private and secure.
How many files can I merge?
You can merge up to 20 files at once. Each file should be under 50MB, and the total row count should not exceed 1 million.
Can I merge CSV files too?
Yes, .xlsx, .xls, and .csv files are all supported. You can even mix different formats in a single merge.
Can I use multiple columns as duplicate criteria?
Yes, you can select multiple columns as a composite key. For example, use 'Order ID' + 'Product Name' together so only rows matching both values are considered duplicates.
Can I tell which file each row came from?
Yes, enable the 'Add source file column' option, and a column will be added showing the original file name for each row.
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How It Works
Each uploaded XLSX file is read as an ArrayBuffer through the File API and parsed using the SheetJS (xlsx) library, which extracts worksheets, cell values, formulas, and formatting. The tool offers multiple merge strategies: row-append (stacking all data vertically), column-match (aligning by header names), or sheet-consolidation (each source file becomes a separate sheet). After merging, SheetJS assembles the combined data into a new XLSX workbook. The output file is generated as a binary Blob and offered for download.
All spreadsheet parsing and merging run entirely in your browser using SheetJS and the File API. No file data is ever transmitted to an external server — your business data remains fully confidential.
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