How to clean a CSV file
- Open your file: CSV, TSV, Excel or JSON. The cleaner scans it straight away and lists what it finds, such as cells with extra spaces, empty rows, duplicate rows and empty columns.
- Click a finding to fix it, or choose an operation from the list for anything more specific.
- Check the preview. Each step is added to the list on the right with what it changed. If something looks wrong, click Undo.
- Download the clean data as CSV (UTF-8, opens correctly in Excel), Excel or JSON.
What it can fix
| Operation | What it does |
|---|---|
| Trim spaces | Removes spaces at the start and end of cells, and optionally collapses double spaces. Hidden spaces are the most common reason a VLOOKUP or join fails. |
| Remove duplicate rows | Compares whole rows or just one key column (for example an email address), ignoring case and spacing if you want. The first row of each group is kept. |
| Remove empty rows | Drops rows where every cell is blank. |
| Change case | Title Case for names and cities, UPPER or lower case for codes and emails, or Sentence case. |
| Find and replace | In one column or all of them, with whole-cell matching, case sensitivity and regular expressions (use $1 for groups). |
| Fill empty cells | With a fixed value such as Unknown, or with the value from the row above or below, which is handy for exports where a group name only appears on the first row. |
| Remove rows where… | Filters out rows where a column is empty, equals or contains a value, or is above or below a number. |
| Standardise dates | Reads 03/14/2024, 14.03.2024, 2024/3/14, Mar 14, 2024, 14 March 2024 and Excel serial numbers, and writes them all in one format, ISO 2024-03-14 by default. Day/month order is detected from the column. |
| Clean numbers | Turns $1,200.00, 1 200 €, 45% and accounting negatives such as (25.00) into plain numbers, with support for decimal commas. |
| Split column | Splits “First Last” into two columns, or any column on a delimiter such as a comma, dash or @. |
| Merge columns | Joins two columns with a separator, skipping blanks. |
| Delete and rename columns | Including one click to rename every header to snake_case for databases and code. |
Private and fast
All cleaning happens in your browser, so you can safely clean customer lists, payroll exports and other confidential files. Files with hundreds of thousands of rows work fine; the preview only draws the rows on screen. When your data is clean, explore it in the CSV viewer, summarise it with a pivot table or chart it.
Frequently asked questions
How do I remove duplicates from a CSV file?
Open the file, then click the “duplicate rows” finding or choose “Remove duplicate rows”. You can compare whole rows or a single column such as an ID or email, and ignore differences in case and spacing. The first occurrence of each row is kept.
How do I remove extra spaces from Excel or CSV data?
Use “Trim spaces”. It removes leading and trailing spaces in every column (or one column) and can also collapse double spaces inside text. The cleaner tells you up front how many cells have extra spaces.
Can it convert dates to one format?
Yes. “Standardise dates” recognises the common date formats, including month names and Excel serial numbers, and writes them all as ISO dates (2024-03-14) or another format you choose. Values it cannot read are left untouched and counted.
Can I undo a change?
Yes. Every step is listed with what it changed, and Undo reverts the last one. Reset goes back to the original file.
Is my data uploaded?
No. The file is read and cleaned by your browser and never sent anywhere.