Excel to CSV Converter & Online Data Cleaner (Free, No Sign-Up)
Data Transformer is a free Excel to CSV converter that also cleans your data as you convert it. Upload an .xlsx, .xls, or .csv file, fix column types, remove duplicate rows, and auto-correct messy values — then download a clean CSV that's ready for Salesforce, Shopify, QuickBooks, Mailchimp, or any database import.
Every step runs locally in your browser, so your spreadsheet is never uploaded to a server. That makes it a safe choice for customer lists, financial exports, and other sensitive data you'd rather not send anywhere.
What this Excel to CSV converter does
📤 Excel to CSV conversion
Upload a .xlsx or .xls file and it's converted into a clean, UTF-8 CSV — no formatting artifacts, no formulas left behind.
🗑 Duplicate row remover
One click scans every row and removes exact duplicates, so mailing lists and product feeds import without rejected entries.
✨ Auto-fix for messy cells
Strips stray characters from numbers, lowercases and trims emails, and standardizes Yes/No values into true/false.
✅ Column-level validation
Assign a type — integer, date, email, URL, boolean, and more — and invalid cells are flagged in red instantly.
Why convert and clean your data before importing it
Most import failures in tools like Salesforce, QuickBooks, Shopify, or Mailchimp aren't caused by the wrong file format — they're caused by inconsistent column types, duplicate rows, or hidden characters left over from Excel. Converting a file without cleaning it just moves the same problems into a new format.
Data Transformer fixes both at once: it acts as an Excel to CSV converter and a lightweight CSV data cleaner, so the file you download on the first try is the file your target system will actually accept.
Column types you can validate
| Type | What gets flagged |
|---|---|
| integer | Any value containing letters, symbols, or decimal points |
| float / double | Non-numeric characters |
| Missing @ symbol or domain | |
| url | Values not starting with http:// or https:// |
| date / datetime | Strings that can't be parsed as a valid date |
| boolean | Anything other than true, false, yes, no, 1, or 0 |
| year | Values that aren't exactly four digits |
| time | Values not in HH:MM or HH:MM:SS format |
Frequently asked questions
How do I convert Excel to CSV online for free?
Upload your .xlsx or .xls file above. Data Transformer reads the workbook, lets you rename columns and set data types, then converts it into a standard CSV you can download in one click — no account required.
How do I remove duplicate rows from a spreadsheet?
Upload your file, then click "Remove Dupes" in the toolbar. The tool compares every row and keeps only unique entries, so you can download a deduplicated file immediately.
Can this tool clean and validate my data, not just convert it?
Yes. Set a data type per column and any cell that doesn't match — like a malformed email or a non-numeric "integer" — is highlighted in red so you can fix it before exporting.
Is my data uploaded to a server?
No. Parsing, cleaning, and conversion all happen locally in your browser using client-side JavaScript. Your file is never transmitted or stored anywhere.
Is this Excel to CSV converter really free?
Yes, with no sign-up, no watermark, and no row limit imposed by the tool itself — only by what your browser can comfortably hold in memory.
