Export CSV files as Excel (XLSX/XLS) format
Convert a CSV file into a genuine Excel workbook (.xlsx) right in your browser. The converter builds the file with the ExcelJS library, so cells carry real Excel types and number formats, header styling, frozen panes, and auto-filter, not just a renamed text file. Output opens cleanly in Excel, Google Sheets, or LibreOffice.
Initializing in your browser…
A non-technical stakeholder needs the data as a real .xlsx with the numbers actually formatted as numbers, not text.
Input
report.csv (12 columns)
Output
report.xlsx, typed cells, frozen header row, auto-fitted columns
A native XLSX is generated with proper cell types so Excel sums and sorts work immediately, avoiding the "numbers stored as text" warning that a plain CSV rename produces. Generation is in-browser, so confidential figures are not uploaded.
Convert a CSV file into a genuine Excel workbook (.xlsx) right in your browser. The converter builds the file with the ExcelJS library, so cells carry real Excel types and number formats, header styling, frozen panes, and auto-filter, not just a renamed text file. Output opens cleanly in Excel, Google Sheets, or LibreOffice.
The workbook is written with ExcelJS, which produces a real Office Open XML (.xlsx) file rather than a CSV with a different extension. Each column gets a detected format: values that are entirely numeric become Number cells (or Currency when a currency symbol is present, Percentage when a "%" appears), values matching YYYY-MM-DD or MM/DD/YYYY become Date cells, and everything else stays Text. You can override any column's format by hand (General, Text, Number, Currency, Percentage, Date, Time) and set the number-format string. Column widths auto-size to the longest value, the header row can be bold with a chosen fill color, the top row can be frozen, and auto-filter can be enabled.
The tool also lets you split data across multiple named worksheets in one workbook. The format selector offers XLSX, XLS, and ODS, but only XLSX is written natively; choosing XLS or ODS produces an XLSX-format buffer (with a notice) because ExcelJS does not emit those formats. A separate CSV output option is available too, which re-serializes the table back to CSV. This is a one-way CSV-to-spreadsheet tool: it reads CSV text only and does not import existing .xlsx files.
Turn raw CSV exports into polished Excel files that business users can open without confusion.
Avoid the common problem of Excel misinterpreting CSV values (like zip codes losing leading zeros) by setting the affected column to Text before converting.
Split your data across separate named sheets within a single Excel workbook.
Set that column's format to Text before converting. Columns auto-detected as Number are stored numerically, which drops leading zeros, so Text is the way to keep them.
No. This tool reads CSV input only and writes an Excel workbook. It does not parse existing .xlsx files.
Rows and columns are parsed and transformed in memory in your browser. No record ever reaches a server.