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CSV Cleaner

Fix a messy spreadsheet export in a minute.

  1. Load a CSV
  2. Pick your cleanups
  3. Check the preview and download

Runs in your browser. Nothing you load here is uploaded or stored.

Step 1

Load your CSV

Paste CSV text instead

No file loaded yet.

Step 2

Pick your cleanups

Nothing changes until you tick a box. The preview updates as you go.

Tidy up
Duplicates
Text case
Emails
Phone numbers
Dates
Split a column
Merge columns
Trim chosen columns
Find and replace
Regex replace
Prefix and suffix
Fixed-value column
Columns: rename, reorder, delete

Untick to delete a column, type to rename it, use the arrows to move it. Includes any columns made by split or merge.

    Load a file to see its columns.

    Step 3

    Preview and download

    Load a file to see a preview.

      Keep going Hand the result to another tool — it stays in this browser.

      • turn a column of dates into calendar events with reminders
      • swap names, emails and phone numbers for placeholders before you share it

      Limits

      • Up to 500,000 rows or 100 MB per file; bigger files stop with a message.
      • The whole file is read into your browser's memory, so very large files need a computer with room to spare.
      • Output is UTF-8; tick "Add a BOM" if Excel shows accents wrongly.

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      Automation & cleanup

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      I build small tools that do it for you, set up for your exact files and the system they go into next.

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      How it works

      Your file is read by this page, on your computer. The cleaning runs in a background worker inside your browser tab, and the download is built on your machine too. There's no server involved. The page is locked down so it can't send data anywhere: it loads no outside scripts, fonts or analytics, and its security policy blocks network requests entirely.

      Pick the cleanups you want, check the preview, and download. They run in this order, so you can predict the result:

      1. Trim spaces from every cell (and the header).
      2. Normalize text case, emails, phone numbers and dates in the columns you choose.
      3. Split one column, then merge columns.
      4. Rename, reorder and delete columns.
      5. Drop empty columns, then empty rows, then duplicate rows.

      Good to know

      • Values it can't read are left alone. A phone cell that says "call me" or a date that says "someday" stays as-is, and the summary tells you how many there were.
      • Ambiguous dates. 03/04/2025 is March 4 in the US and 3 April almost everywhere else. By default the cleaner looks at the whole column. If any date has a day above 12 in the first position, it reads the column as day-first; otherwise it assumes US order. You can force either one.
      • Two-digit years 00–49 become 2000s; 50–99 become 1900s.
      • Phone numbers keep extensions (+18015550123 x12). E.164 output needs a country code. Numbers written without one get the default you set (1 for US and Canada).
      • Big files. Tens of megabytes are fine on a typical laptop. The preview shows the first 100 rows, but every cleanup and the download apply to the whole file.
      • Excel. If accented names look garbled when you open the result in Excel, tick "Add a BOM" before downloading.