About CSV Analyzer Online
This CSV analyzer opens on the Summary view: one card for each column of your file, showing its type, how many values it has and, for numbers, the mean, median, minimum, maximum and standard deviation. It is free, needs no sign-up and runs in your browser, so nothing you enter is uploaded.
Drop a .csv, .tsv or .txt file of up to 20 MB, or paste CSV text. The file is parsed in a background worker, so a large one does not freeze the page. The Overview tells you how many rows and columns were read, how many values are missing and which delimiter was detected, which is the quickest way to catch a file that was split in the wrong place. An Excel workbook opens the same way.
Text columns show the count, the number of unique values and the missing count. Numeric columns add the statistics, using the sample standard deviation, and a column is numeric when at least 95 percent of its non-missing values are numbers, so one stray word does not hide the statistics. The download button saves the cards as a table with extra Q1, Q3 and excluded columns, handy for a data dictionary or a report appendix.
How to use CSV Analyzer Online
- Drop a file onto the box, tap it to choose one, or paste a copied file. CSV, TSV, TXT, XLSX and XLS files up to 20 MB are accepted. To paste text instead, use the text box below it.
- For a workbook with several sheets, choose the sheet from the Sheet list that appears.
- Read the Overview: rows, columns, missing values, the delimiter and any columns that held stray values.
- Open Summary for per-column statistics, then Profile for types, percentage missing, distributions and the stray values.
- Open Correlation to see how the numeric columns move together, with blue for positive and red for negative.
- Open Preview to read the rows, 50 per page. Type in the filter box to keep matching rows, and press a column header to sort.
- Open Chart, pick a chart type and a column (two for a scatter plot), or press Open Chart Maker for more chart types.
- Press the download button in Summary to save the column statistics as a CSV file.
Features
- Open .csv, .tsv, .txt, .xlsx and .xls files up to 20 MB, or paste a file or text.
- Parsing runs in a Web Worker for files and pastes, never on every keystroke. The paste box waits half a second after you stop typing.
- Automatic delimiter detection among comma, semicolon, tab and pipe, with quoted fields and a leading byte-order mark handled.
- Excel support through SheetJS, loaded only when a workbook is opened, with a sheet picker.
- Columns are tracked by position, so two columns with the same header stay separate. The second one is shown as "name (2)".
- Majority-type inference: a column is numeric when 95 percent or more of its non-missing values are numbers, and a date column on the same rule. Stray values are listed.
- Missing values recognised as empty cells, NA, N/A, NaN, null, none, nil, a single or double dash and #N/A, in any letter case.
- Per-column count, missing, unique, mean, median, quartiles, minimum, maximum and sample standard deviation.
- Minimum and maximum are found with a loop, so columns of hundreds of thousands of values are safe.
- Pearson correlation matrix of the numeric columns (the first 30 when there are more), using only rows where both values are present.
- Paged preview, 50 rows per page, with a filter and sortable headers, inside a scroll area that works on a phone.
- Chart builder: bar chart of counts, histogram and scatter plot, plus a link to Chart Maker.
- Download of the per-column summary as a CSV file.
Worked examples
name,age,score,city with five rows (the built-in sample) gives age: mean 32, median 30, std 6.6708. score: mean 79.6, median 79, std 12.341. city: 4 values, 2 unique, 1 missing.
A summary CSV download for that sample gives Header: column,type,count,missing,excluded,unique,mean,median,std,min,q1,q3,max. The age row reads age,number,5,0,0,5,32,30,6.670832,25,28,35,42.
Numbers in the download are rounded to six decimals.
Privacy: how it works
- Files are read by your browser and parsed by JavaScript in a worker on this page. The contents are not sent to Ulkaa or to any other server. The Excel reader is part of this site and loads from it, not from a third party, and only when you open a workbook.
- Nothing is stored. Reloading the page clears everything. The summary CSV is created on your device when you press the download button.
Tips
- If a column you expected to be numeric shows as text, open Profile and read its stray values. A currency symbol, a decimal comma or a word is usually the cause.
- Check the missing count before looking at averages. A mean computed from only 60 percent of the rows can mislead.
- A correlation matrix only covers numeric columns. Encode a yes or no column as 1 and 0 first if you want it included.
- Quote any field that contains your delimiter, such as "1,200" in a comma file, so the row keeps its column count.
- For a very large file, open it instead of pasting it. The paste box is meant for small pastes.
- Delimiter detection looks at the first five lines. Make sure they use the same separator as the rest.
Frequently asked questions
Is it really free?
Yes. There is no price, no trial and no credit card. Ulkaa Tool does the work with your own device, so there is no server bill to pass on to you.
Do I need an account?
No. There is no sign-up and no login. Open the page and use it. An Ulkaa account is not needed for anything on this tool.
Does it run in my browser?
Yes. Your data are processed by code running in your browser tab, on your own device.
Is my data uploaded?
No. Your data are never sent to Ulkaa or to anyone else. You can check this yourself by watching the Network tab in your browser developer tools while you use the tool.
What file can I open?
A delimited text file such as .csv, .tsv or .txt, or an Excel .xlsx or .xls workbook, up to 20 MB, with one row per record and a header row of column names. Commas, semicolons, tabs and pipes are detected automatically.
Which standard deviation does it show?
The sample standard deviation, dividing by n - 1, calculated over the numbers in the column.
Why does a numeric-looking column show as text?
A column is numeric when at least 95 percent of its non-missing values are numbers. If more than 5 percent are words, currency symbols or decimal commas such as 1,5, it reads as text. The Profile view lists the stray values.
More CSV, Excel and Data Analyzer pages
- CSV, Excel and Data AnalyzerOpen a CSV, TSV or Excel file, or paste text, and profile every column: types, missing values, statistics, charts and correlations.
- CSV Viewer OnlineLook at your CSV as a table, with a filter box and sortable columns.
- Excel Data AnalyzerOpen an Excel workbook, pick a sheet and get column statistics.
- Excel Viewer OnlineOpen an Excel file, choose a sheet and read it as a table.
- Correlation Matrix OnlineA Pearson correlation matrix of every numeric column in your data.
- Data Profiling Tool OnlineA column-by-column profile of a CSV, an Excel sheet or a pasted table.