What is a CSV / Excel cleaner?
A spreadsheet cleaner helps you find repeated records, missing values, and inconsistent formatting without writing formulas or code. This free tool analyzes your file using deterministic rules and shows the actual before and after values before you approve a change.
How to clean your spreadsheet
- Upload a file or try a synthetic sample. Choose a worksheet for an Excel workbook.
- Review the quality dashboard and suggested fixes. Select the columns you want to change.
- Choose an operation, inspect its preview, and apply it. Compare with the original, undo, or reset whenever needed.
- Download CSV, XLSX, or JSON, or export a cleaning summary with no sensitive cell contents.
How to remove duplicate rows
Review exact duplicate groups before removal. By default, all columns are compared. Select fewer columns to match records by email or another key, or deselect a unique ID column to ignore it. You can optionally ignore case or normalize whitespace for comparisons. Removal always keeps the first matching record in the current order.
How to fix missing values
Empty cells, whitespace-only text, and your configured markers can count as missing. Replace them with custom text, zero, or the mean or median of recognized numbers in a column. Alternatively, remove rows missing required values. Numeric zero, false, and the text “0” are never missing by default.
How to standardize spreadsheet formatting
Trim whitespace without collapsing line breaks, choose capitalization explicitly, and conservatively normalize email domains while preserving the local portion. Dates require a source rule when ambiguous. Number conversion uses your chosen locale, retains protected identifier columns, and skips values with leading zeros or more than 15 digits. Currency symbols are removed without currency conversion; percentages become fractions. Phone formatting uses a selected country and a bundled parsing library, leaving invalid or ambiguous values unchanged.
Supported file formats and limits
Import UTF-8 CSV or TSV, XLSX, legacy binary XLS, and JSON arrays of flat objects. CSV supports quoted fields, escaped quotes, embedded newlines, and comma, semicolon, tab, or pipe delimiters. The default limit is 5 MB, 50,000 data rows per sheet, 200 columns, and 1,000,000 cells across a workbook. XLSX archives must expand to less than 64 MB. Export CSV, XLSX, or JSON. Excel imports preserve displayed values as strings; exports contain values, without original formulas, styles, macros, charts, or merged-cell layout. XLSX exports retain all worksheet names; CSV and JSON export the selected sheet.
Privacy and browser processing
Your files stay in your browser. Parsing, scans, cleaning, and exports run in a local Web Worker. File contents are never uploaded, sent to analytics, or saved to browser storage. Clear File releases the dataset and history. Processing libraries are served by this website and loaded only when needed. Spreadsheet exports escape formula-like text; JSON preserves data values.
Frequently asked questions
Will this change my original file?
No. The browser reads your file and creates a separate download. Your original import is retained in memory for comparison and reset.
Can it resolve an ambiguous date like 04/05/2026?
Only after you choose day/month/year or month/day/year as the source rule. With automatic recognition, ambiguous dates are flagged and kept unchanged.
Does it verify email addresses or phone ownership?
No. Email checks identify common structural issues, not mailbox existence or delivery. Phone checks use numbering rules and do not establish whether a number is active or owned by anyone.
Can I clean more than one worksheet?
Yes. Switch worksheets to review and clean each independently. Changes and history are retained for each sheet. XLSX downloads include the entire values-only workbook.
Where can I find test data?
Use the four built-in synthetic presets or create reproducible records with the DummyDetails Mock Data Generator. The JSON Formatter can help inspect JSON before import.