Convert CSV to formatted Excel with bold headers and auto-width columns. Free, private, runs in your browser.
100% private — your files never leave your browser. All processing happens locally on your device.
Drop a CSV, TSV, or TXT file here, or click to browse
CSV files are plain-text data files with no formatting, no formulas, and no visual structure. XLSX is Microsoft Excel's rich format that supports bold text, cell colors, column widths, frozen panes, auto-filters, data validation, and much more. Converting CSV to XLSX transforms raw data into a professional, formatted spreadsheet that's ready for presentation, analysis, or sharing with colleagues who expect polished Excel files.
Opening a CSV in Excel often produces ugly results — columns too narrow, dates reformatted incorrectly, leading zeros stripped from zip codes, and no visual hierarchy. This tool solves all of that by creating a properly formatted XLSX file with bold headers, auto-adjusted column widths, a frozen header row for scrolling, and smart type detection that preserves your data exactly as intended. The result looks like a spreadsheet someone took the time to format manually.
The tool uses PapaParse to parse your CSV with auto-detected delimiters and ExcelJS to create a professionally formatted Excel file. Smart type detection identifies numbers, dates, and text to apply appropriate cell formats — importantly, values like zip codes ('00123') are stored as text to prevent Excel from stripping leading zeros. The output includes bold header formatting, auto-adjusted column widths, a frozen top row, and auto-filters on the header for easy data exploration.
Yes. All processing happens locally in your browser. Your CSV data is never uploaded to any server. The tool creates the XLSX file entirely in memory using JavaScript and downloads it directly to your device.
Yes. The output includes bold header rows, auto-adjusted column widths, and a frozen header pane for easy scrolling. It's not just raw data — it's a properly formatted spreadsheet.
The tool uses smart type detection. Zip codes like '00123' are stored as text to prevent Excel from stripping the leading zeros.
Yes. The tool auto-detects the delimiter (comma, tab, semicolon, pipe) but you can override it manually.
Absolutely. All processing happens in your browser. Your CSV data is never uploaded to any server.