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CSV Cleaner

Clean up messy CSV data

Clean up a messy CSV in your browser. Pick the cleaning steps you want, see what changes, and download the tidied file. Each step is a separate switch, so you never get transformations you did not ask for.

The defaults handle what breaks imports most often: stray leading and trailing spaces, blank rows padding the end of a file, inconsistent line endings from mixed Windows and Unix tooling, smart quotes pasted in from a word processor, and invisible characters such as zero-width spaces and a leftover byte order mark. Any of those can make an otherwise valid value fail a lookup or a validation rule.

The riskier operations are off by default and stay that way until you enable them. Stripping leading zeros will destroy ZIP codes and product codes, and dropping empty columns changes your schema — both are useful when you mean them, and damaging when they happen silently.

Files stay on this deviceRuns entirely in your browserFree — no signup

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Accepts CSV, TSV, TXT. Maximum input: 10 MiB. Files above this hard limit are rejected before local processing.

How to Use

  1. Upload your CSV file or paste CSV data
  2. Enable the cleaning steps you want and leave the rest off
  3. Review the cleaned preview
  4. Download the cleaned CSV

Features

  • Trim leading and trailing whitespace from every cell
  • Remove empty rows, and optionally empty columns
  • Strip invisible characters including zero-width spaces and the BOM
  • Normalise smart quotes to straight quotes
  • Standardise mixed line endings across the file
  • Optionally standardise null-like values such as N/A and NULL
  • Optionally strip leading zeros — off by default, since it destroys ZIP codes
  • Every step is individually switchable, and nothing runs unless you enable it

Use Cases

  • Fix an export that fails an import validation for no visible reason
  • Strip trailing spaces that break lookups and joins
  • Remove blank rows and columns left behind by a spreadsheet
  • Clean text pasted from a word processor or a PDF
  • Normalise a file before merging or comparing it with another
  • Prepare a messy dataset for analysis

Frequently Asked Questions

What does the CSV cleaner actually change?

Only the steps you enable. Each cleaning operation is a separate switch — whitespace trimming, empty row removal, invisible character stripping, quote normalisation, line-ending standardisation, and a few more — so nothing is transformed behind your back.

Why does my CSV fail to import when it looks fine?

Usually something invisible. A trailing space, a zero-width character, a byte order mark at the start of the first header, or a smart quote pasted from a document all look identical to clean data on screen and all break exact-match validation.

What is a BOM and why does it matter?

A byte order mark is an invisible character some tools write at the start of a file. It attaches itself to your first column name, so a header that reads id fails to match id. Stripping it fixes the mismatch.

Will cleaning damage my ZIP codes or product codes?

Not unless you ask it to. Stripping leading zeros is off by default precisely because it turns 01234 into 1234 and ruins postal codes, phone numbers, and padded identifiers.

What does removing empty columns do?

It drops columns that contain no values in any row. Useful for exports padded with unused fields, but it changes the shape of your file, so it is off by default.

What are null-like values?

Text placeholders such as N/A, NA, NULL, and none that stand in for missing data. Standardising them makes empty values consistent so downstream tools treat them the same way.

Is my file uploaded anywhere?

No. Cleaning happens in your browser and the file contents are not sent to the app server.

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