About

Spreadsheet data pasted into a CMS or codebase without conversion produces broken layouts, invisible tab characters, and accessibility failures. This tool parses the tab-separated value (TSV) format that Excel and Calc place on the clipboard, then outputs standards-compliant <table> markup with proper <thead> and <tbody> semantics. All cell content is HTML-entity-escaped to prevent cross-site scripting. Output optionally includes Bootstrap table classes for rapid integration into existing frameworks.

The converter handles quoted fields per RFC 4180 rules: a cell containing a literal tab, newline, or double-quote is preserved correctly when wrapped in double-quotes by the spreadsheet application. Limitation: merged cells in the source spreadsheet are flattened into the top-left cell value only. Column count is normalised to the longest row; short rows receive empty <td> elements to keep the grid rectangular.

Formulas

The conversion pipeline follows a deterministic three-stage process:

Stage 1: splitRows(input) → split on CRLF | LF | CR respecting quoted fields

Stage 2: splitCols(row) → tokenise on U+0009 (TAB), handling double-quote escaping per RFC 4180

Stage 3: render(grid) → map each cell through escapeHTML then wrap in <td> or <th>

Where grid is a 2D array of dimensions R × C, with R = number of non-empty rows and C = max(cols_i) across all rows. Padding rule: if len(row_i) < C, append (C − len(row_i)) empty strings.

Reference Data

Feature	Description	Default
First Row as Header	Wraps first row cells in <th> inside <thead>	Enabled
Bootstrap Classes	Adds table table-striped table-bordered to <table>	Disabled
Compact Output	Removes indentation and newlines from HTML output	Disabled
Tab Character	U+0009 Horizontal Tab - Excel clipboard delimiter	-
Newline Handling	Supports CR, LF, and CRLF line endings	Auto-detect
Quoted Field Rule	Fields containing tabs or newlines are wrapped in double-quotes by Excel	RFC 4180
HTML Escaping	& → &, < → <, > → >, " → "	Always
Max Columns Detected	Longest row determines column count; shorter rows are padded	-
Empty Cell Output	Generates <td></td> for blank cells	-
Clipboard API	Uses navigator.clipboard.readText() with fallback to manual paste	-
Copy Output	Copies generated HTML to clipboard via Clipboard API or execCommand fallback	-
Download	Exports output as .html file via Blob URL	-
LocalStorage	Persists input text and options across sessions	Enabled
Semantic Markup	Uses <thead>, <tbody>, <th scope="col">	When header enabled
Accessibility	Output table includes role and aria attributes guidance	-

Frequently Asked Questions

Excel and Calc wrap such cells in double-quotes when copying to the clipboard, following RFC 4180 conventions. The parser detects opening double-quotes and treats all content - including tabs and line breaks - as part of a single cell until a closing double-quote is found. A literal double-quote inside a quoted field is escaped as two consecutive double-quotes ("").

Trailing empty cells in a spreadsheet row may not produce trailing tab characters on the clipboard. The converter normalises all rows to the maximum column count by appending empty elements, ensuring a rectangular HTML table that renders correctly in all browsers.

When the "First Row as Header" option is enabled, header cells use inside , which satisfies WCAG 1.3.1 (Info and Relationships). For full compliance, you should also add a element describing the table purpose - the converter does not generate one automatically because it cannot infer the semantic meaning of your data.

The tool is optimised for TSV (tab-separated) input, which is the native clipboard format of Excel and Calc. Comma-separated data will be treated as single-column rows. For CSV conversion, replace commas with tabs in a text editor first, or re-copy directly from your spreadsheet application.

No. The clipboard plain-text representation strips all formatting metadata. Only raw cell values are transferred. If you need styled output, export the spreadsheet as HTML directly from Excel (File → Save As → Web Page), though this produces bloated markup compared to the clean semantic output this tool generates.

Enabling Bootstrap adds class="table table-striped table-bordered" to the element. No additional wrapper divs or responsive containers are added - you should wrap the output in a

yourself if horizontal scrolling is needed on narrow viewports. The option targets Bootstrap 4 and 5 class naming conventions.