Normalize messy date formats in CSV files. Convert MM/DD/YYYY, DD-MM-YYYY, timestamps, and 30+ formats to ISO 8601 (YYYY-MM-DD). Handle US/UK ambiguity. Perfect for database imports and Excel. 100% browser-based.
Drop your CSV file with messy date formats. Files stay in your browser, never uploaded.
Choose which columns contain dates. neatcsv auto-detects date columns for you.
Select ISO 8601 (YYYY-MM-DD) or custom format. Specify US/UK for ambiguous dates.
Get CSV with normalized dates ready for database import or Excel analysis.
Problem: Some rows have "12/31/2023", others "2023-12-31", some "Dec 31 2023"
✓ Solution: neatcsv detects all formats and converts to single format (ISO 8601)
Problem: "01/02/2023" - is it Jan 2 (US) or Feb 1 (UK)?
✓ Solution: Specify US (MM/DD/YYYY) or UK (DD/MM/YYYY) format. neatcsv converts consistently.
Problem: "1672531200" (Unix timestamp) or "2023-12-31T23:59:59Z" (ISO 8601 with time)
✓ Solution: Convert timestamps to dates. Extract date from datetime. Preserve or remove time component.
Problem: "44927" (Excel serial date) instead of readable date
✓ Solution: Convert Excel serial numbers to ISO 8601 dates (44927 → 2023-01-01)
Upload your CSV to neatcsv, select date columns, and choose the target format (ISO 8601 recommended). The tool converts 30+ date formats: MM/DD/YYYY, DD-MM-YYYY, Month DD YYYY, timestamps, and more. Free for up to 10,000 rows (Starter plan, 9€/month).
ISO 8601 is the international standard: YYYY-MM-DD (e.g., 2023-12-31). It's unambiguous, sorts correctly as text, and works universally in databases, Excel, APIs. We recommend converting all dates to ISO 8601.
01/02/2023 could be Jan 2 (US format) or Feb 1 (UK format). neatcsv lets you specify: 1) Interpret as US (MM/DD/YYYY), 2) Interpret as UK (DD/MM/YYYY), or 3) Mark as ambiguous for manual review. Always specify format to avoid errors.
Yes. Excel stores dates as numbers (e.g., 44927 = Jan 1, 2023). neatcsv detects Excel serial numbers and converts them to readable dates in ISO 8601 format.
Invalid dates (e.g., "32/01/2023", "2023-13-45") are flagged in the validation report with line numbers. You can: 1) Keep original value, 2) Mark as empty, or 3) Set a default date. neatcsv never silently corrupts data.
You choose: 1) Convert to date only (2023-12-31), 2) Keep date and time (2023-12-31 23:59:59), or 3) Keep full ISO 8601 with timezone (2023-12-31T23:59:59Z). Most databases prefer date-only or ISO 8601 with time.
Convert 30+ formats to ISO 8601. Handle US/UK ambiguity. From 9€/month.
Start Fixing Dates