XLSX Viewer: Browse an Excel File Online

Choose an .xlsx file and each worksheet appears as a tab. The grid is virtualised: only the rows and columns on screen are drawn, so a sheet with more than 100,000 cells scrolls smoothly instead of freezing the page. Column widths are set automatically, and you can switch between Narrow, Auto and Wide when long text gets cut off. The first row can be treated as a header or as ordinary data with one toggle, and the row and column counts update to match.

Click a column header to sort it, and use the search box to filter rows that contain your text in any cell. Sorting and filtering do not change the file. They change the view, which is also what the export uses.

Download the current sheet as CSV or JSON. The export respects the filter and the sort, so if you searched for one customer and sorted by date, you get exactly those rows in that order. That makes the viewer a quick way to move spreadsheet data into a script, a Mongo import or a test fixture without opening Excel. Paste the JSON into the JSON formatter or turn it into TypeScript interfaces with the related tools.

Dates come out as ISO dates, for example 2026-03-14, which is easier for code to read than the display format Excel used. When you export to CSV, remember that the target program decides how to read each column: an id such as 00123 is kept as text here, but may lose its leading zeros if you reopen the CSV in Excel.

The viewer reads the file with the read-excel-file library and shows the values Excel last saved. Formulas are not recalculated, so you see the cached result; if a workbook was generated by a script that never calculated its formulas, those cells can be empty. Charts, images, conditional formatting, cell colours and fonts, merged-cell layout, pivot tables and macros are not displayed.

Only the modern .xlsx format is supported. Legacy .xls and the binary .xlsb format cannot be opened, so re-save them as .xlsx first. Files up to about 30 MB are accepted, and the whole sheet is held in memory, so very large workbooks may be slow on a phone. If a number looks different from what you see in Excel, the cause is usually number formatting, since the viewer shows the stored value rather than the formatted text.