Monu Tools

CSV to Fixed-Width Flat File Converter

Convert CSV into an aligned fixed-width flat file, padding each column to its widest value. Runs entirely in your browser.

Reverse: Flat file → CSV

How to use the CSV → flat file

  1. 01

    Paste your CSV into the left panel, or type it in.

  2. 02

    Pick the delimiter your CSV uses; the fixed-width text updates instantly on the right.

  3. 03

    Copy the fixed-width text with the copy button.

What it does

This tool turns CSV into a fixed-width flat file, padding every column to the width of its longest value so the columns line up in a monospace font.

Fixed-width files are still required by many legacy and mainframe systems; this produces one without a script.

Private and unlimited

Every conversion happens locally in your browser, so your data is never uploaded, logged or stored on a server. You can use it on confidential exports without a second thought, and it keeps working offline once the page has loaded.

There is no sign-up, no watermark and no row limit: the only ceiling is your device's memory.

Frequently asked questions

Which delimiter should I use?

Comma is the standard. Pick semicolon in regions where the comma is the decimal separator (common in German and other European exports), tab for TSV files, or pipe when your values already contain commas.

Is there a row or file-size limit?

There is no fixed row cap or daily quota. Because everything runs locally the practical limit is your device's memory, which comfortably handles the tens of thousands of rows most exports contain.

Is my data uploaded anywhere?

No. The conversion runs entirely in your browser with client-side JavaScript, so nothing you paste or drop ever leaves your device. That makes it safe for spreadsheets that contain customer emails, financial figures or other sensitive data.

Sources

Embed this tool

Add this tool to your own website. Copy the snippet below; it stays up to date automatically.

<iframe src="https://monu.tools/embed/en/csv-to-flat-file" width="100%" height="640" style="border:1px solid #e5e5e5;border-radius:12px;max-width:680px" loading="lazy" title="Monu Tools"></iframe>

Related tools

CSV → multi-line

Turn each CSV row into a readable block of "Header: value" lines, separated by blank lines. Runs entirely in your browser.

CSV → GeoJSON

Convert CSV with latitude and longitude columns into a GeoJSON FeatureCollection of points. Runs entirely in your browser.

GeoJSON → CSV

Flatten a GeoJSON FeatureCollection into CSV: feature properties become columns, with longitude and latitude added. Runs in your browser.

CSV → KML

Convert CSV with latitude and longitude columns into KML placemarks for Google Earth and Maps. Runs entirely in your browser.