Make CSV safe for Excel — free, no upload

Neutralize spreadsheet formulas, preserve identifiers and date-like text, and export CSV or explicitly typed XLSX without uploading your file.

Make a CSV open more safely in Excel by neutralizing formula-like values, preserving leading-zero and long numeric identifiers and date-like text, normalizing surrounding whitespace, and adding a UTF-8 BOM to CSV output by default. The detected input delimiter is preserved. Processing stays in your browser with no upload and accepts one file at a time. You can download CSV up to 300 MB or XLSX up to 25 MB. CSV is capped by processing time: the next tested rung with many columns exceeded the wait budget while memory stayed low. XLSX is capped much lower because spreadsheet generation uses substantially more memory as input grows, even on its streaming path. XLSX writes every value as text; CSV keeps risky source values from being interpreted directly by wrapping them in a spreadsheet-safe text form.