CSV INTEGRITY LAB

Usage guide

A local workflow, with the limits visible before you start.

1. Open the web preview

Use the live demo in an updated desktop Google Chrome browser. JavaScript, Web Workers and downloads must be enabled. No installation or account is needed for this web preview. The Chrome extension package is not yet published or verified as installed.

2. Try fictional sample data

Choose Try sample data. The sample contains leading zeros, a long ID, formula-like text, a date-like string and an uneven row. The warning counts should each show one.

3. Inspect your local file

Choose a CSV, TSV or TXT file. Set the encoding and separator used by the source. If columns appear combined, check the separator. If decoding fails, confirm the encoding with whoever supplied the file; the tool does not automatically detect it.

4. Review warnings

The preview lists at most 100 examples with their row and column. Counts can exceed the displayed examples. Date-like and formula-like warnings are conservative: a warning is not a confirmed error. No value is automatically corrected.

5. Download XLSX

Choose Export Excel — all cells as text. Your browser creates a workbook named after the source file with a -text-safe.xlsx suffix. It contains one worksheet named Data. Keep the source CSV for comparison.

Numbers, dates and formulas remain strings. Numeric sums and date calculations require deliberate conversion of the appropriate columns in your spreadsheet application. The tool cannot restore zeros or digits already changed in the source.

6. Clear the file

Use Clear file or close the tab. Working data is held in browser memory; downloaded files remain on your device until you delete them. The page does not intentionally persist source files in cookies, local storage or a server database.

Limits and errors

• 2 MB per file; 10,000 rows; 200 columns; 200,000 total cells.
• Maximum 32,767 UTF-16 code units per cell; one file/worksheet at a time.
• UTF-8, Windows-1252, Windows-1258 or UTF-16 LE; comma, semicolon or tab separator.
• A 15-second worker timeout stops slow parsing or export. Try a smaller file after a timeout.
• Malformed quoting, invalid decoding, invalid Unicode and unsupported XML control characters stop export instead of silently changing values.
• After an error, export is disabled until a valid file is loaded.

Compatibility and support

The web flow and generated files have been checked in Chrome and with an independent XLSX reader (openpyxl). Native Excel/LibreOffice rendering, other browsers, mobile browsers and actual extension installation are not yet verified. Independent-reader tests do not guarantee every spreadsheet version behaves identically.

Email [email protected] with your browser version, chosen encoding/separator and error message. Send a minimal fictional example rather than personal, financial or confidential data.