Excel Format Online - Free Styled Spreadsheet Export

ComTools Excel Format exports Excel, CSV, JSON or HTML tables as professionally styled .xlsx workbooks. Choose from classic blue/green/gray/purple/red themes; freeze and filter headers; zebra stripes; date, datetime and decimal formats (including custom); column width and row height; URL hyperlinks; optional sensitive-field masking. Preview the first 10 rows after upload with live refresh as you change options, then export all rows. Excel/CSV/JSON files are processed on the server and deleted immediately; HTML is parsed locally in the browser before row data is submitted. Settings are saved to browser localStorage for your next visit.

Upload Excel / CSV / JSON / HTML file

Style

Data Formatting

Date

Datetime

Decimal

Table Header

Freeze

Filter

Font Bold

Font Size

Font Color

Cell Color

Table Body

Zebra Striping

Col Width

Width (px)

Row Height

Height (px)

Advanced

Append hyperlink

Enable Data Masking

7 uses

Free Excel / CSV / JSON / HTML Online Formatter

Key features

Multi-format import
Supports .xlsx, .xlsm, .xltx, .xltm, .csv, .json and .html/.htm. JSON accepts object arrays or 2D arrays; HTML reuses the Html to Excel table parser.
Header and theme styles
Five classic color themes; freeze first row, enable filter, bold text, custom font size and font/background colors for headers.
Data type formats
Date, datetime and decimal presets plus Custom Excel format strings (e.g. yyyy-MM-dd, #,##0.00).
Body layout and advanced options
Zebra striping, auto/fixed column width and row height, URL hyperlinks, optional masking for phone numbers and emails.
Preview then export
See a 10-row styled preview on upload; any option change refreshes instantly; export applies settings to all rows as a downloadable .xlsx.

Use cases

Polish reports before delivery
Turn CSV / JSON into styled Excel
Convert web HTML tables to workbooks
Mask sensitive fields before sharing

How to use

Open Excel Format and configure theme, header, data formats, column width and row height in the collapsible settings panel.
Upload a .xlsx, .csv, .json or .html file.
Review the 10-row preview table and check header colors, zebra stripes and number/date formats.
Adjust any format option; the preview refreshes automatically.
Click Export Excel to download the fully formatted .xlsx file.

Configurable format options

Theme: classic blue, green, gray, purple or red — one click for header and zebra colors.
Header: freeze first row, auto-filter, bold, font size 8–24, custom font and fill colors.
Data formats: date (incl. dd MMM yyyy), datetime, decimal (percent and thousands); all support Custom format codes.
Layout: zebra rows, column width / row height (auto or fixed max), hyperlinks, field masking.

Excel Format FAQ

QWhich file formats does Excel Format support?

.xlsx, .xlsm, .xltx, .xltm, .csv, .json, .html and .htm (legacy .xls is not supported). JSON can be an array of objects (one row per object) or a 2D array. HTML tables and div grids are parsed automatically. Output is always .xlsx (Open XML), compatible with Microsoft Excel, WPS and LibreOffice.

QIs Excel Format free? Do I need to sign up?

Completely free with no signup or login required. Preview and export have no usage limits and no fees.

QAre uploaded files stored on the server? Is my data safe?

Excel, CSV and JSON files are uploaded for preview and export, then deleted immediately with no backup or long-term storage. HTML is parsed locally in your browser; only row data is sent, not the original HTML. Do not upload confidential files; enable field masking before external sharing.

QWhat is the difference between preview and export?

Preview shows only the first 10 rows and refreshes live as you change format options, so you can quickly check header colors, zebra stripes and number/date formats. Export applies all current settings to the full dataset and downloads a .xlsx file. For large sheets, preview first, then export.

QHow do I set custom date, datetime and decimal formats?

In Data formatting, choose Custom for date, datetime or decimal, then enter an Excel format code such as yyyy-MM-dd, yyyy-MM-dd HH:mm:ss, #,##0.00 or 0.00%. Codes match Microsoft Excel and work in Excel and WPS after export. Examples: date yyyy-MM-dd, currency #,##0.00, percent 0.00%.

QHow does sensitive-field masking work? Which columns are affected?

Enable masking under Advanced options. On export: columns whose headers contain email, phone, mobile or tel, or cells that look like emails or phone numbers, are partially hidden; columns with password or secret in the header show ******. Use before external delivery; masking is irreversible—keep a backup of the original file.

QIs there a file size limit? Are format settings saved?

Maximum upload size is 100 MB per file; split very large files with the Excel Split tool first. Format options (theme, header, data formats, etc.) are saved in browser localStorage (key comtools.excel-format.v1) and restored on your next visit in the same browser.

QHow is this different from Html to Excel? Which should I use?

Html to Excel converts HTML tables to TSV text in the browser for paste into Excel—nothing is uploaded. Excel Format is for downloading a styled .xlsx: more source formats plus themes, freeze panes, filters, zebra stripes, number formats, hyperlinks and masking. Choose Format for professional styled output; choose Html to Excel for plain text only.

Excel formatting guide

Consistent header styling and number formats improve readability when delivering reports or sharing data externally. Enable freeze panes and filters for large sheets; use yyyy-MM-dd for dates and #,##0.00 for currency; turn on masking to hide middle digits of phone numbers and emails. ClosedXML applies styles server-side and outputs standard Open XML compatible with Microsoft Excel, WPS and LibreOffice.

Date: yyyy-MM-dd | dd MMM yyyy

DateTime: yyyy-MM-dd HH:mm:ss

Decimal: #,##0.00 | 0.00% | #,##0.000