Open Excel and OpenDocument spreadsheets without Excel

What it shows

• Every sheet, as a tab. Sheets hidden in Excel are listed and marked hidden. Sheets set to very hidden are marked too. Excel's Unhide menu does not list those at all; only a macro or the VBA editor can show them. You can open both kinds here like any other sheet.
• The cells, with Excel's row numbers and column letters, in a grid that draws only the rows on screen. The file is parsed in a background worker, so a sheet of 50,000 rows scrolls without freezing the tab.
• Each cell's value and formula. Tap or click a cell and the line under the grid shows it as the spreadsheet displays it (1,334.00), the value actually stored (1334), and the formula as written (=SUM(B3:B4)). Cells with a formula have a green bar on their left edge.
• Merged ranges and dates. A merged title is outlined and the cells it covers are shaded. Above the grid, the merged ranges are listed by address, such as A1:C1. Dates use the cell's own format (9/21/26), and the cell detail gives the ISO date (2026-09-21), which means the same thing in every country.
• Save this sheet as CSV. The sheet is saved as a CSV file from this tab. Each cell is written the way the sheet displays it, as Excel's own CSV save does. Every row gets the sheet's full width. The file is UTF-8 with a byte-order mark, so Excel opens accented names such as Ærø correctly.
• A one-line summary: the number of sheets and how many are hidden, each sheet's rows × columns, and how many formulas the workbook holds. Links in cells, comments and references to other workbooks are shown as plain text.

What it cannot do

• Charts, pivot tables and pictures. Charts, images and shapes placed on a sheet are not drawn. A pivot table shows as the plain cells it last produced, and chart sheets appear as a tab with nothing in it.
• Formatting. Colours, fonts, borders, column widths and conditional formatting are not shown. Number formats are applied, so amounts, percentages and dates look as they do in Excel.
• Recalculation. Formulas are not recalculated. You see the value that was saved with the file. A file written by a program that never calculated its formulas has no saved values, so those cells show only their formula.
• Macros. VBA macros in .xlsm, .xlsb and .xls files never run. When a workbook has a macro project, the page says so. Only the cells are read.
• Password-protected workbooks. A workbook with a password to open it is encrypted, and viewhack cannot decrypt it; it is named as password-protected. Sheet protection and “protect workbook structure” are different: they only block editing, and those files open here normally.
• External links and data connections. Links to other workbooks, web queries and database connections are never refreshed or fetched. The values shown are the ones last saved in this file.
• Very large workbooks. The whole file is read into the tab's memory. In a test, a 50,000-row × 10-column workbook (6.6 MB, 500,000 filled cells) took 1.7 s to parse and about 60 MB to hold, roughly 120 bytes per filled cell. A workbook with tens of millions of filled cells can run out of memory, especially on a phone, and will not open. For a huge export, a CSV opens in the CSV viewer, which reads a file in slices.
• Apple Numbers files are not opened; export them from Numbers as .xlsx first.

Useful to know about spreadsheet files

.xlsx, .xlsm, .xlsb

Excel's format since 2007 is a ZIP of XML files, one per sheet, plus a shared list of strings. .xlsm is the same with a vbaProject.bin holding macros. .xlsb stores the same parts in a binary form, which makes big files faster to open. A sheet holds at most 1,048,576 rows × 16,384 columns (A1 to XFD1048576).

.xls (Excel 97–2003)

Excel's older binary format (BIFF8) lives in a Microsoft compound file, the same container as a Word .doc. The sheets are in a stream named Workbook, which is how viewhack tells an .xls from a .doc before opening it. A sheet holds at most 65,536 rows × 256 columns (IV65536).

.ods (OpenDocument)

This is LibreOffice Calc's format, a ZIP whose content.xml holds every sheet. Formulas are stored as of:=SUM([.A2:.A3]), which is shown here in Excel's notation, =SUM(A2:A3).

How Excel stores a date

A date is a plain number, the days since 30 December 1899, with a number format that says “show this as a date”. 46286 is 21 September 2026, and 46286.5 is noon that day. The number has no time zone, so it is read here as written and does not shift with your clock. Workbooks from old Mac Excel count from 1904 instead, and that is detected.

Hidden and very hidden sheets

A hidden sheet is one right-click away in Excel (Unhide). A very hidden sheet is set from the VBA editor and does not appear in that list. Both still hold ordinary cells, and they sometimes hold the numbers a summary sheet is built from. Check them before you forward a workbook.