Line Counter

Line counting is essential for developers tracking code size, writers managing structured content, and data analysts auditing list completeness. This tool instantly counts total lines, non-empty lines (lines with content), and empty lines (blank lines or whitespace-only lines). It also provides a line-numbered view so you can reference specific lines by number.

Real scenarios: a developer pasting the output of a log-tail command to count how many unique error lines fired during an incident window; a QA lead verifying that a CSV export contains the expected row count before a database import (import with the wrong count silently drops rows); a poet checking stanza lengths in a villanelle before submission (which demands exact 19-line structure with strict repetition rules). Each needs different line interpretations — non-empty lines for the log case, total lines for the CSV case, structure-aware counting for the poem.

Under the hood, the counter splits on any of the three common line-ending conventions: LF (\n, used by Unix/macOS), CRLF (\r\n, used by Windows/HTTP), and legacy CR (\r, used by classic Mac OS up to version 9). It normalizes them all to LF before splitting, so a CSV saved on Windows counts the same as the same CSV saved on Linux. Empty-line detection strips whitespace first, so a line containing only spaces or tabs is treated as empty — which matches how most programmers mentally classify blank rows. Large inputs (tens of megabytes) process in under a second because the split operation is O(n) over the string length.

Limitations worth knowing: if your text has no trailing newline, the counter reports the visible line count rather than 'line count plus one for the implicit EOF line' that `wc -l` uses on Unix; this tool’s behavior is what people expect when they’re visually counting. Compared to running `wc -l` in a terminal, this tool works on any device, shows non-empty and empty separately, and avoids the platform-specific off-by-one behavior. If you also need to measure character count or words in the same text, the Word Counter shows both stats alongside the line count. All processing happens locally in your browser.