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Detect a CSV delimiter without uploading the file

Find whether a delimited file uses commas, tabs, semicolons, pipes, or another common separator. The browser compares candidate structures and reports confidence, expected columns, line endings, and encoding clues.

What you get

  • Comma, tab, semicolon, pipe, and colon comparison
  • Candidate scores based on consistent record widths
  • Line-ending and UTF-8 BOM identification
  • Local scanning with no file-processing request
Browser-only processing

JavaScript reads the selected file on this device. No file content is sent to DataOlllo, Vercel, analytics, or another server.

Choose a local CSV to inspect

The detector compares common separators and checks record consistency in your browser.

or drag and drop the file here

No file transferNo processing API or cloud storage.
No file loggingNames and contents are not sent to analytics.
Source unchangedThe browser only reads your selected file.

Why a CSV may not use commas

CSV is often used as a general name for delimited text. European exports frequently use semicolons when commas are decimal separators. Database tools may emit tab-separated files, and logs or integration feeds sometimes use pipes. A .csv filename therefore does not prove that the separator is a comma.

Choosing the wrong delimiter makes an entire record appear in one column or splits values in unexpected places. Detection is a useful first step when a spreadsheet, database importer, or analytics platform opens a file incorrectly.

  • Comma-separated exports
  • Tab-separated TSV data
  • Semicolon-delimited regional files
  • Pipe-delimited system feeds

How the detector chooses a candidate

The browser samples records and parses each candidate while respecting quoted values. A strong candidate produces more than one column and repeats the same column count across many records. The displayed confidence combines that consistency with the distance from competing candidates.

Confidence is evidence rather than certainty. Free-text data, malformed quotes, mixed delimiters, single-column files, or an unusual separator can produce ambiguity. The candidate table makes that uncertainty visible instead of silently forcing a comma.

  • Quoted separators are not treated as boundaries
  • Multiple candidate scores remain visible
  • Expected column width is reported
  • Uneven records are counted during the full scan

Inspect sensitive exports privately

The selected file is read inside a Web Worker created by this page. No multipart form, Vercel function, API endpoint, object-storage upload, or server-side CSV library receives the file. Results are calculated on the device and disappear when the page is closed or reset.

This is useful for customer lists, financial exports, operational reports, healthcare-adjacent datasets, or any file that should not be sent to an unfamiliar conversion service. Always follow your organization’s policies for handling regulated data, even when using local software.

Common questions

What delimiters can the tool detect?

It compares comma, tab, semicolon, pipe, and colon candidates. The candidate table shows the inferred column count and structural consistency for each one.

Is a TSV file supported?

Yes. Choose a .tsv, .csv, or plain-text file. A detected tab is displayed as TAB so it is visible rather than rendered as whitespace.

Can delimiter detection be wrong?

Yes, especially for single-column, very short, mixed, or malformed files. That is why the page reports a confidence score and alternative candidates rather than presenting the guess as infallible.

Does DataOlllo store a sample of my file?

No. Sampling and the full structural scan occur in browser memory. No field values, headers, filename, or file bytes are submitted to the server.

Continue your workflow

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Reviewed and updated July 21, 2026