Add Prefix/Suffix to Lines — Wrap Each Line

Add Prefix/Suffix is a self-contained text processing workspace. Add a prefix and/or suffix to every line of text. Open the page, get the result, close the tab — that is the entire workflow.

Most people land on Add Prefix/Suffix via a search at the moment they actually need the tool. That shapes the design: the page is a single screen with the input on one side, the controls in the middle, and the result on the other, so a first-time visitor can complete the job without reading documentation.

Add Prefix/Suffix performs the transformation entirely inside the JavaScript runtime. Your file lives in the tab's memory while the engine works on it; the result lives in the tab's memory until the browser triggers the download. Both are released when the tab closes, the way every browser tab releases its memory.

Behind the controls you see, standard browser APIs is doing the actual text processing. Formats are detected on load and the engine produces a deterministic output for any given input + options combination — useful when you need to re-run a job and expect identical results.

The only practical limit is the 0 MB per-file ceiling, which keeps the tool responsive across a wide range of devices. Run the tool ten times in a row, run it ten thousand times — it behaves the same way and produces the same quality of result.

If you fit any of these descriptions, Add Prefix/Suffix should slot cleanly into your workflow: translators aligning bilingual passages; researchers normalising scraped text; support agents standardising replies. The tool keeps the controls focused on what matters for each of these use cases.

The output handed back by Add Prefix/Suffix is the output file. If you would prefer to keep the result in the browser instead of downloading it, you can copy it from the result panel and paste it directly into another tab — useful when the next tool in your workflow expects pasted text rather than a file.

Once you have used Add Prefix/Suffix, the natural next steps depend on what you are doing with the result. Common follow-ups include Add Line Numbers, Text to List, and Sort Lines. These are surfaced on the page so you do not have to hunt the catalog manually.

Add Prefix/Suffix keeps the control set focused. Every option on the page is there because a real workflow needs it, and the defaults aim at the most common case so a first-time user can get the right output without changing any settings.

Some background on the design choices behind Add Prefix/Suffix: every option you see on the page is there because a real workflow needs it, and every option that is not shown has been deliberately omitted to keep the common case fast. The bias is toward minimal-but-complete.

If you also use a command-line tool for add prefix/suffix, Add Prefix/Suffix is a convenient alternative for the times you are on a different machine or helping someone who is not comfortable in a terminal. The output is a standard file in the format documented above.

Pro tip: Add Prefix/Suffix works just as well in a private/incognito window as in a normal one, which is occasionally useful when you want zero browser-history footprint of the job. Another tip: if the tool ever feels slow, it is almost always because the browser tab is competing for CPU with another tab — pausing or closing the heavy ones gives the engine room to work.

For most failure modes, refreshing the page and re-running the job is enough — the engine has no persistent state to corrupt. If the same input fails twice in a row, the input itself is most likely the problem (a truncated file, an unexpected variant of the format, or a stream the engine does not recognise).

Add Prefix/Suffix is intentionally narrow in scope so the common case is fast and the result is predictable. If you ever need a variation it does not cover, browse the rest of the catalog — there is a good chance an adjacent tool already exists, and switching between tools is just a matter of opening another tab.