Count CSV rows locally in your browser

Counting newline characters works only for simple files. A valid CSV field can contain a line break when the value is enclosed in quotes. In that case, one logical record occupies multiple physical lines, and a basic line counter reports the wrong number.

This tool parses quote boundaries and escaped quotes while reading the file in chunks. It reports both logical CSV records and physical text lines so you can use the number that matches your import limit, audit, or data-quality check.

• Quoted line breaks stay inside a record
• CRLF and LF endings are recognized
• A likely header is separated from data records
• Trailing newlines do not invent an extra record

Selecting a file gives JavaScript in this page permission to read that local file. The browser passes it directly to a Web Worker, which scans small chunks and returns summary numbers to the page. There is no upload endpoint, server action, temporary cloud file, or server-side parser in this workflow.

The source stays unchanged. DataOlllo does not send filenames, headers, field values, or file contents to analytics. Ordinary website assets and privacy-safe page analytics may use network requests, but the selected file data is not included in them.