Online Excel (XLSX & XLS) Spreadsheet Viewer
Explore multi-sheet Excel workbooks, sort columns, filter rows, and export sheets to CSV locally in your browser without Microsoft Excel.
Drag & drop files here, or click to browse
Open single or multiple files simultaneously in tabs
🔒 Your files stay on your device. We never upload your files to any server.
Inside Excel Workbooks (.XLSX & .XLS) & High-Speed Browser Grid Inspection
Microsoft Excel workbooks (.xlsx and legacy .xls) power financial modeling, inventory tracking, scientific datasets, and operational reporting worldwide. Modern .xlsx files use the Office Open XML SpreadsheetML specification—a ZIP-compressed package containing xl/workbook.xml, individual worksheet XML files (xl/worksheets/sheet1.xml), and a shared string table (xl/sharedStrings.xml) that deduplicates repeated text values across thousands of cells.
Opening large spreadsheets through cloud-based office portals requires uploading potentially sensitive financial projections, payroll rosters, or customer lists to remote servers, and often re-evaluates volatile formulas or strips original formatting. Worse, opening an untrusted spreadsheet in a desktop application can trigger external data connections or macro prompts.
FilePeek parses both modern .xlsx (PK ZIP container) and legacy .xls (OLE2 Compound Document 0xD0 0xCF 0x11 0xE0) workbooks 100% locally in your browser using SheetJS and renders them inside a high-performance virtualized data grid. You can switch between worksheet tabs, sort any column ascending or descending, search across cells in real time, and export the active sheet to CSV—all while your financial and operational data stays strictly on your own machine.
Technical Specifications
Architectural details and file format parameters verified by FilePeek.
| Supported Formats | Excel Open XML (.xlsx) & Excel 97–2004 (.xls) |
|---|---|
| Binary Signatures | 50 4B 03 04 (.xlsx ZIP) / D0 CF 11 E0 (.xls OLE2) |
| Maximum Workbook Size | 500 MB Local Browser Processing |
| Grid Virtualization | Windowed row rendering for 50,000+ rows at 60fps |
| Multi-Sheet Support | Full bottom/top sheet tab switcher with row/col counts |
| Export Capability | One-click active worksheet export to standard UTF-8 CSV |
How to Open & View XLSX Viewer Files
Step-by-step instructions for viewing files without installing desktop software.
Select Your .XLSX or .XLS Workbook
Drag and drop your Excel file onto the dropzone above or click "Browse Files" to open it from your local drive.
Switch Between Workbook Sheets
Click any worksheet tab in the spreadsheet bar to inspect different tables, summary sheets, or raw data tabs.
Filter, Search & Sort Columns
Type into the instant search filter bar to narrow down matching rows, or click any column header to sort values ascending or descending.
Export Active Sheet or Download Original
Export the currently viewed worksheet directly to a clean .csv file for downstream tools, or download the original workbook.
XLSX Viewer Viewer Features
Modern browser utilities designed for clarity, performance, and privacy.
Multi-Sheet Workbook Navigation
Detects every worksheet inside your .xlsx or .xls file and lets you switch sheets instantaneously without reloading.
Virtualized High-Speed Row Scrolling
Renders only the visible viewport slice so spreadsheets with tens of thousands of rows scroll effortlessly without browser lag.
Sticky Row Numbers & Column Headers
Keeps Excel-style A, B, C column letters and header labels pinned at the top while you scroll deep into large datasets.
Instant Full-Sheet Search & Row Filtering
Filter thousands of rows in milliseconds by typing any SKU, account number, name, or value into the toolbar search box.
Interactive Column Sorting
Click any column header to sort numeric and alphabetical values ascending or descending with clear visual indicators.
One-Click CSV Sheet Export
Convert and download the active Excel worksheet as a standards-compliant UTF-8 CSV file directly from your browser.
Common Real-World Scenarios
How professionals and casual users rely on FilePeek's local engine daily.
Quickly sanity-check schema columns, row counts, and null values in client-supplied .xlsx exports before ingesting them into data pipelines.
Search vendor price lists, inventory SKUs, and shipping manifests on the warehouse floor or while traveling.
Review general ledger exports and trial balances locally without risking accidental edits or cloud synchronization.
XLSX Viewer Frequently Asked Questions
Answers to common questions regarding XLSX Viewer rendering and privacy.
Can I view Excel files with multiple tabs/worksheets?
Yes. FilePeek reads all worksheets inside your .xlsx or .xls file and provides a sheet tab bar so you can switch between every sheet effortlessly.
Does FilePeek modify my original Excel file when I sort or filter rows?
No. FilePeek operates strictly in read-only mode in browser memory. Sorting and filtering only change your on-screen view; your original file on disk is untouched.
How does FilePeek handle very large spreadsheets with 20,000+ rows?
FilePeek uses viewport row virtualization, meaning only the rows currently visible on your screen are mounted in the DOM, keeping memory low and scrolling smooth.
Are formulas evaluated or are cached values displayed?
FilePeek displays the computed values stored inside the workbook cells without executing potentially dangerous external macro scripts or network calls.
Can I convert an Excel sheet to CSV using FilePeek?
Yes! Every worksheet includes an "Export Sheet to CSV" button in the viewer toolbar that generates and downloads a clean CSV file locally.
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