View and Edit CSV Files Without Uploading Them
BigWow's CSV Viewer reads your files directly from your local file system using the HTML5 File API and parses them in browser memory. Your spreadsheet data is never transmitted to any server.
Parses CSV files of up to 100,000 rows entirely in browser memory.
0 bytes of spreadsheet data are uploaded to any server.
Supports sort, filter, and CSV/JSON export — all processed locally.
Frequently Asked Questions
Is it safe to open confidential CSV files in a browser tool?
With BigWow, yes. Your CSV is read via the HTML5 File API — sandboxed local access. The file data stays in your browser's memory and is never uploaded.
Can I view Excel (.xlsx) files in addition to CSV?
Yes. BigWow uses the SheetJS library compiled locally to parse .xlsx files directly in your browser without any server conversion step.
Sources & References
- WHATWG File API specification for client-side file access.
- RFC 4180 Common Format and MIME Type for Comma-Separated Values (CSV) Files.
Try it now — 100% free, zero upload
No account, no ads, no file size limits. Opens instantly in your browser.