Excel strips leading zeros, turns codes into dates, and mangles long numbers into scientific notation. Drop your file in — we detect it and fix it.
or click to browse — .csv, .xlsx, .xls
Excel stores numbers without leading zeros, so 01234 becomes 1234. This tool detects code-like columns (ZIP codes, IDs, phone numbers) where zeros were stripped and pads values back to the expected width. Then download the Excel-safe .xlsx — it stores those columns as text so Excel won't strip the zeros again when you reopen it.
Excel auto-detects values like 3/4, or gene names like SEPT1, as dates and stores them as serial numbers (e.g. 45355). The cleaner detects date columns that were converted to serial numbers and turns them back into readable dates (YYYY-MM-DD).
Long numbers like 1234567890123 get displayed as 1.23457E+12. The tool detects scientific-notation values and expands them back to full numbers. One caveat: if Excel already rounded the number when it saved the file, the lost trailing digits can't be recovered — the tool flags those cases so you know.
Nothing is uploaded. The entire tool runs in your browser with JavaScript — your file never leaves your device and is never sent to any server. The page is even blocked (by its content-security policy) from making network requests at all.
Yes — drop in .csv, .xlsx or .xls. You can download the cleaned result as CSV, or as an Excel-safe .xlsx that keeps the fixed columns as text so Excel won't re-corrupt them.
Imagine what we'd build for your team — data pipelines, dashboards, and infrastructure that never corrupts a value or drops a row.
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