Markdown Table Validator
Paste a Markdown table or drop a .md file to instantly check its structure. Validates the separator row, column count consistency, alignment markers, duplicate or empty headers, and previews the rendered table. Nothing leaves your browser.
Markdown Table
OR DROP A FILE
Drop a .md or .markdown file here, or
Supports .md and .markdown files up to 10 MB
⛔
Wrong file type — only .md or .markdown files are supported. You dropped a file.
Validation Errors
Warnings
✓ Valid Markdown Table
Column Headers
Data Preview (first 5 rows)
How It Works
1
Paste or drop your tablePaste Markdown table syntax directly into the text area, or switch to file mode and drop a
.md file. The validator extracts all table blocks it finds.2
Structure analysisThe validator checks the separator row syntax, scans every data row for column count consistency, reads alignment markers (
:---, ---:, :---:), and detects header issues.3
Review the reportGet a pass/fail result plus full stats: row count, column count, alignment per column, empty cells, duplicate headers, and a rendered data preview.
What Gets Validated
- Separator row — checks that the second row exists and contains only valid separator cells (
---,:---,---:,:---:). Missing or malformed separators are errors. - Column consistency — every row is compared against the header column count. Rows with too many or too few cells are flagged with their line number.
- Alignment markers — reads leading/trailing colons in each separator cell to detect left, right, center, or default alignment per column.
- Duplicate headers — checks the header row for repeated column names (case-insensitive), which can confuse parsers and tooling.
- Empty header names — flags columns whose header cell is blank, as these render as invisible columns in most Markdown renderers.
- Pipe structure — warns if leading or trailing pipes are inconsistent across rows, which can cause rendering differences between Markdown processors.
- Empty cells & rows — counts blank data cells and warns about entirely blank rows that may indicate accidental extra lines.
- Data preview — renders the first 5 data rows in a formatted table with alignment applied so you can visually confirm the structure looks correct.
🔒 Privacy & Security
All validation is performed locally using the Web File API and the FileReader API. Your Markdown content is never sent to a server. Suitable for internal documentation, private wikis, or any sensitive table data.