Free online CSV to HTM converter

A browser, intranet, email attachment, or static website may require tabular data as a web page rather than a plain-text dataset. Converting the file creates an HTML table that can be opened in a browser, shared, or archived as a readable snapshot.

What the CSV format is

CSV (Comma-Separated Values) is a plain-text format for records and fields. Each record usually occupies one line, and fields are separated by commas, although semicolons, tabs, and other delimiters are also used. Fields containing delimiters, line breaks, or quotation marks are normally enclosed in double quotation marks.

Spreadsheet applications such as Microsoft Excel and LibreOffice Calc export CSV files. Databases, content-management systems, analytics platforms, and web applications use CSV for portable data exchange. CSV stores values and basic row-and-column structure, but not spreadsheet formulas, charts, cell styles, comments, or multiple worksheets.

What the HTM format is

HTM is a three-letter filename extension for an HTML (HyperText Markup Language) document; .html is the equivalent four-letter extension. An HTM file can contain elements such as <table>, <tr>, <th>, and <td>, which a browser renders as a page.

Unlike CSV, HTML can add headings, hyperlinks, styles, colors, alignment, and page structure. It is suitable for publishing a static table, opening data locally, attaching a web document, or archiving a human-readable version. HTML does not automatically provide sorting, filtering, or editing; those functions require JavaScript or a web application.

How to convert CSV to HTM

LibreOffice Calc provides delimiter controls and a preview before export:

1. Open the CSV in Calc.
2. In the import dialog, select the source encoding, delimiter, and text-quoting character. Check that fields appear in the correct columns and that accented characters display correctly.
3. Optionally format the header row, adjust column widths, add a page title, or apply basic cell styles.
4. Choose File → Save As, select HTML Document (.html) or the available HTML format, and save the file.
5. If a receiving system specifically requires .htm, rename the resulting .html file after saving. The extension change does not alter the HTML content.

Microsoft Excel can perform the same export: open or import the CSV, verify the delimiter and encoding, then choose File → Save As and select the available Web Page or HTML file type. The exact name and availability of that option vary between Excel versions.

For a conversion without installing software, upload the file to 101convert.com, choose HTM as the output format, run the conversion, and download the generated file.

Automated conversion with Python

For repeatable conversions, Python's csv module handles quoted fields, while html.escape() prevents data from being interpreted as markup:

import csv
import html

with open('data.csv', newline='', encoding='utf-8-sig') as source:
    rows = csv.reader(source)
    with open('data.htm', 'w', encoding='utf-8') as target:
        target.write('<!doctype html><html><head><meta charset="utf-8"></head><body><table>')
        for row_number, row in enumerate(rows):
            tag = 'th' if row_number == 0 else 'td'
            cells = ''.join(f'<{tag}>{html.escape(value)}</{tag}>' for value in row)
            target.write(f'<tr>{cells}</tr>')
        target.write('</table></body></html>')

Save the script as convert.py and run python convert.py. Change utf-8-sig when the source uses another encoding. For a semicolon-delimited file, configure the reader with csv.reader(source, delimiter=';').

Quality and compatibility caveats

CSV has no universal delimiter, encoding, date format, or character-set declaration. Incorrect import settings can split quoted values into extra columns or produce garbled text. Keep <meta charset="utf-8"> in the generated page when the output is UTF-8.

Use HTML escaping for imported values containing <, >, or &. Without escaping, data can damage the table markup or inject unintended HTML and scripts. A basic conversion preserves values and row order, not formulas, charts, conditional formatting, comments, or separate worksheets.

Very large CSV files can create slow-loading HTM pages because the browser must render the entire table. Filter or paginate the data before export, or use a database-backed web application for large datasets.