Free CSV to chart previewer
Drop in a CSV export from your shop, till, accounts or booking system. You'll see what each column contains, any problems in the data, totals, a monthly trend and a top-10 breakdown. It takes seconds and nothing is uploaded.
Private by design: your file is read by this page on your own computer. The page has a browser security policy (connect-src 'none') that blocks it from making any network requests, so your data can't be sent anywhere. No account, no cookies, no analytics.
No file to hand? Try a fictional sample: (or download them: clean, messy)
Summary
Columns detected
| Column | Type | Filled | Quick stats |
|---|
Trend
Breakdown
Need more than a preview?
This free previewer shows one file, two charts and no saving. The Offline KPI Dashboard ($29) is the full version. It's one HTML file you keep and use offline, with up to 12 KPI tiles, several chart types, filters and date ranges, "vs previous period" comparisons, layouts that re-apply to next month's export, print to PDF and filtered CSV export.
See the Offline KPI Dashboard on Contra ($29)
Rather have it built for you? I turn spreadsheets into a live ops dashboard in 5 days: see the fixed-price service on Contra.
I'm the maker, Chris Elder (London). The previewer stays free whether or not you buy anything.
How it works
The page reads the first line as column headings and works out the separator. It then checks each column. Mostly numbers (including £1,234.50, (45.00) as a negative, and 12%) makes a number column. Mostly dates (2026-03-04, 04/03/2026, 4 Mar 2026) makes a date column. A few repeated values makes a category. Everything else is text. Cells it can't read are counted under Data checks rather than guessed.
FAQ
Is my file uploaded anywhere?
No. The file is read by JavaScript in your browser tab. The page's security policy blocks all network connections, and the sample files are built into the page. Close the tab and the data is gone.
Can I open an Excel (.xlsx) file?
Not directly. In Excel use File → Save As → CSV. In Google Sheets use File → Download → Comma-separated values. Then drop the CSV here.
My dates look wrong.
Dates like 03/04/2026 can be 3 April (UK) or 4 March (US). If every date in the column fits both, the page assumes UK and says so in Data checks. Switch it with "Dates like 03/04/2026 are" above the trend chart.
Numbers like 1.234,56 aren't read.
Decimal-comma numbers aren't supported, so they're flagged rather than misread as a different value.
Is there a row limit?
Files up to 50 MB. Large files depend on your computer's speed.