Nothing is uploaded. When you open a file the Excel Viewer reads it locally with the browser’s File API, unzips and parses the .xlsx workbook in memory with a bundled JavaScript engine, and renders every worksheet on your device. There is no server, API, database or tracking in the processing path, so a payroll sheet, client list, budget or any other sensitive spreadsheet stays on your machine. Searching, sorting, selecting cells and exporting all run locally too, the tool works offline once cached, and closing the tab discards everything. The only optional network use anywhere on the site is consent-gated advertising, which never sees your file or its contents.

The viewer aims to render your workbook the way Excel does. A file with several worksheets shows a row of tabs so you can switch between them, and each keeps its own dimensions, sort and search. Formula cells display the cached result value the spreadsheet last calculated (the viewer does not re-run the formula, it reads the stored result), so a SUM or VLOOKUP shows its number rather than the formula text. Merged cell regions are honoured with the correct row and column spans; frozen header rows are detected and kept sticky as you scroll; dates are formatted in a readable ISO style; and number formats such as percentages, currency symbols and fixed decimals are applied. Rich text and hyperlink cells are flattened to their visible text, and cells that contain an Excel error are shown clearly.

Beyond just displaying the data, the Excel Viewer gives you three ways to work with it read-only. The search box scans every cell in the current sheet and highlights the matches, showing a running count so you can find a value fast. Clicking any column header sorts by that column — ascending, then descending, then off — and the sort is number-aware, so numeric columns sort by value rather than as text, while a header row is detected and kept pinned on top. Selecting cells (click, Shift-click for a range, or Ctrl / Cmd-click for a scattered set) produces an instant summary in the status bar: the count of non-empty cells plus the Sum, Average, Min and Max of any numbers in the selection — the same quick totals Excel shows at the bottom of its window — all computed locally in your browser.

The viewer reads modern Excel workbooks (.xlsx, .xlsm and the template variants .xltx / .xltm) as well as delimited text files (.csv, .tsv, .txt), auto-detecting the delimiter for CSV. The legacy binary .xls (BIFF) format and OpenDocument .ods are not supported — open them in Excel or LibreOffice and save as .xlsx or .csv first, and the tool tells you so with a clear message. Files up to 100 MB are accepted. For getting the data out, you can export the sheet you are viewing to CSV (UTF-8 with a byte-order mark and CRLF line endings so Excel reopens accented text correctly), to JSON (an array of objects keyed by your first-row headers, or an array of arrays when there is no header), or to a self-contained HTML table, and there is a Print option. It is a read-only viewer, so it does not save edits back into the original .xlsx.