# Font File Inspector & Glyph Coverage

> Read TTF and OTF family names, styles, metrics and Unicode character coverage. Upload a single TrueType or OpenType font to inspect its names, weight, width, italic flag, variable-font presence, units, glyph count and license text when present. Check which non-whitespace characters in your sample map to nonzero glyphs. This file tool uploads to the server; Type Lab inspects fonts locally.

Part of usefulweb.site (https://usefulweb.site/). Results are deterministic calculations from the inputs and the listed assumptions; the API returns exactly what the web page shows.

## Use it
- Human interface: https://luminafontinspector.usefulweb.site/ (interactive tool at https://luminafontinspector.usefulweb.site/tool)
- JSON API: POST https://luminafontinspector.usefulweb.site/api/v1/calculate with a JSON object of inputs (schema: https://luminafontinspector.usefulweb.site/api/v1/tool)
- OpenAPI: https://luminafontinspector.usefulweb.site/openapi.json
- MCP (Streamable HTTP): https://luminafontinspector.usefulweb.site/mcp - tool `lumina_font_inspector`

## Inputs
- font (file, required): Font (TTF or OTF; up to 2 MB; uploaded to the server)
- text (textarea): Text to check (whitespace excluded)

## Method
- Read one sfnt TrueType or CFF OpenType file, validate bounded table ranges, and prefer English Windows Unicode name records, then Unicode and ASCII Macintosh records. Names and license fields are limited to 1024 characters. No font is installed or executed by this tool.
- Read OS/2 weight and width, italic selection, head units, maxp glyph count and the presence of fvar. Font checksums, outlines, shaping and font safety are not validated.
- Coverage uses the preferred Unicode cmap format 12 or 4. A nonzero glyph index counts as covered; whitespace is excluded. Without a supported cmap, coverageKnown is false and per-character coverage is unknown. This does not test shaping, ligatures, emoji sequences or visual quality.
- License text is read from available name records and normalized for display. Missing metadata does not establish usage rights. WOFF, WOFF2, collections and compressed fonts are not supported.