CSV Cleaner & Validator guide.

One clear goal

Clean a UTF-8 CSV using rules you choose, and download an error report showing what was found. The browser processes the data locally; no file is uploaded.

Start the downloaded tool

1. Download and extract the ZIP from your Gumroad receipt or Library.
2. Open index.html in a current Chrome, Edge, Firefox or Safari browser. Keep all files in the same folder.
3. Choose your CSV or load the fictional sample. The full download accepts up to 5 MB, 200 columns and 50,000 data rows. The hosted demo accepts 20 data rows.
4. Select a delimiter if automatic detection is wrong. Choose trimming, blank-row removal, duplicate removal and whether invalid rows should be excluded.
5. Choose each column's expected type and whether it is required. Dates use YYYY-MM-DD; numbers use a dot decimal separator.
6. Review and clean. Inspect the preview and issue counts, then download the cleaned CSV, full error report and summary JSON.

What changes

The original file is never overwritten. Values are not automatically converted, so leading zeros remain intact. Exact duplicates are compared after optional trimming. Rows with the wrong number of columns are always excluded and reported. Other invalid rows remain unless you explicitly choose exclusion.

Spreadsheet formula protection is on by default. It adds an apostrophe to fields beginning with =, +, - or @, including negative numbers. Turn it off only when your receiving system needs original values and you trust the file. Source record numbers count logical CSV records, including the header; a quoted multiline record counts once.

Screenshot

Limits and privacy

UTF-8 CSV/text only. XLSX, binary files and UTF-16 are rejected. Email validation checks basic structure, not whether an address exists. The tool does not infer business rules, verify customers or promise that cleaned data is correct for every downstream system. Review the report and keep your original file.

The portable tool has no analytics or upload endpoint and works without an account or internet connection. It links to optional online documentation and support only when you choose those links.

Purchase and support

£19 once for version 1.0.0, source, sample and this guide. The licence covers one purchaser or business for internal use and allows modifications. Do not resell the application or source. Your exported data belongs to you. Installation support is available for 90 days after purchase; future versions and ongoing hosted access are not promised. Applicable statutory rights remain unaffected.