CSV Cleaner & Converter

Clean a messy CSV or convert CSV to JSON — in your browser

Spreadsheet exports are rarely tidy: stray spaces around values, empty rows left behind by deleted data, the same record pasted twice, inconsistent line endings. This tool fixes those common problems and, for developers, converts between CSV and JSON both ways — entirely in your browser, so the file never leaves your device and there's nothing to upload.

How to clean a CSV file

1. Drop your .csv file onto the box above, or paste the rows straight into the text area.
2. Tick the passes you want: trim whitespace, remove blank rows, remove duplicate rows.
3. Click Clean CSV. You'll see exactly how many rows went in, how many came out, and how many blanks and duplicates were removed.
4. Click Download CSV to save the cleaned file.

What each pass does: trim whitespace strips leading and trailing spaces inside every cell — the single most common reason two values that look identical won't match. Remove blank rows drops rows that are entirely empty. Remove duplicate rows keeps the first occurrence of each identical row and drops the rest. You choose which to apply, so nothing changes that you didn't ask for.

How to convert CSV to JSON (and JSON back to CSV)

CSV → JSON turns your file into a JSON array of objects, using the header row as the keys — the shape most APIs, scripts, and config files expect. Empty header cells become positional keys like column_3 so no column is ever silently dropped, and ragged rows with missing trailing cells are filled with empty strings rather than throwing an error.

JSON → CSV does the reverse: paste an array of objects and it produces a CSV whose columns are the union of every object's keys, so objects with different fields still line up into one consistent table. Both directions run through the same battle-tested parser used for cleaning, so quoting, commas inside values, and embedded newlines are handled correctly.

Why do this locally instead of on an upload site?

CSVs are where sensitive data lives: customer lists, transactions, email addresses, exports from your CRM or bank. Uploading one to a random web tool just to tidy it is exactly the habit worth breaking. Here the parsing runs in your own browser — there is no server that ever sees a single row. You can confirm it in your browser's network inspector, and the tool keeps working with your connection switched off.

Working with large CSV files

The tool holds your file in memory while it works, so very large CSVs can strain a phone's memory. If a file is large you'll get a heads-up before processing rather than a silent crash, and on a desktop you have far more headroom. For multi-hundred-megabyte files, a desktop browser is the safer choice.