What is a line counter?
A line counter is a text-analysis tool that counts every line break in a piece of text, including blank lines, and reports supporting stats like non-empty line count, longest line, and duplicate lines. This one runs entirely as JavaScript inside your browser — there's no upload and no server round-trip, so your file never leaves your device. Every count updates live as you type or paste.
How lines are counted
The tool splits your text on every line break and counts the resulting segments, including empty ones. This mirrors the Unix wc -l convention and how code editors display line numbers: a block of text with 10 line breaks contains 11 lines. Blank lines — including trailing blank lines at the end of a file — are counted the same way.
How duplicate lines are detected
A line is flagged as a duplicate if the same trimmed text appears more than once anywhere in your input. This is useful for finding repeated rows in a CSV export, redundant entries in a config file, or copy-pasted lines in a script. Turn on "Ignore case" if capitalization shouldn't count as a difference — for example, when comparing usernames or tags.
Who uses a line counter
- Developers — count lines of code, check file size limits, or estimate effort for a code review.
- Data analysts — count rows in a CSV or TSV export before importing it elsewhere.
- Sysadmins — scan log files for line counts and spot repeated error lines.
- Writers & poets — count lines in poetry, scripts, or lyrics where line breaks carry meaning.
- Subtitle editors — check subtitle or caption files where each line has a strict length limit.
Common line-count use cases
| Use case | What line count tells you |
|---|---|
| Source code files | Rough size/complexity of a file (lines of code) |
| CSV / TSV exports | Number of data rows, often minus a header line |
| Log files | Number of log entries, and how many are duplicated |
| Subtitle (.srt) files | Number of caption blocks and per-line length |
| Poetry & lyrics | Structural line count for verses or stanzas |