CSV Formula Checker: what to check
Formula-like values are warnings, not definite malicious content. This check does not execute formulas or automatically sanitize your business data.
CSV text can become a spreadsheet instruction
CSV itself is plain text, but a spreadsheet may interpret a cell beginning with =, +, -, or @ as a formula or instruction. The result depends on the application and its import settings. Opening a file and importing a column explicitly as text can behave differently.
The checker looks for common leading formula markers, including after whitespace or selected invisible prefixes. Ordinary negative numbers such as -10 are excluded from this warning. A plus-prefixed telephone number may still be flagged because it is ambiguous, not because it is known to be harmful.
Review intended values instead of rewriting them silently
Legitimate formulas, account labels, and telephone numbers can all resemble formula input. CommaMend preserves their literal strings in data exports. It does not run formulas, fetch a referenced URL, prepend an apostrophe to every business value, or certify that a CSV is safe in every spreadsheet.
For an untrusted file, use the receiving application’s text-import controls and security guidance. Edit a value manually only if you know it is wrong. You can skip a warning to keep the intended value exactly as it is. No guessed substitute is proposed for this category.
Understand the difference between data and reports
The downloadable error report prefixes formula-like report fields with an apostrophe to reduce the chance that the diagnostic report executes content when opened. That report protection does not change the original CSV or its data download. Treat this checker as a practical review aid, not a complete security audit or a guarantee of spreadsheet behavior.
Try a real CSV example
| Label | Value |
|---|---|
| Calculation | =SUM(1,2) |
| Phone | +441234567890 |
| Balance | -10 |
The first value is a formula and the second could be an intentional phone number. Both deserve review. The ordinary negative number -10 is not flagged by this formula-prefix check.
Download the example CSVSelect the example in the tool above. Your file is processed locally, and changes require your approval.