What is the difference between TTF and OTF?

The outline format. TrueType uses quadratic curves in a glyf table; OpenType may use either that or PostScript cubic curves in a CFF table. Both live in the same SFNT container, and OpenType adds GSUB/GPOS typography tables.

What does fsType mean?

A field in the OS/2 table encoding the foundry's embedding permissions — installable, editable, print-and-preview only, or restricted. It is a licensing signal that PDF generators and browsers are expected to honour.

Why is a character showing as a box?

The font's cmap has no glyph for that code point, so the renderer substitutes a fallback. Inspecting the cmap coverage confirms it immediately.

TrueType / OpenType Inspector

Read font tables, name records, glyph counts and licensing flags.

on the roadmapFile Format & Archivesfree · no sign-up

This bench is being wired up

The font-inspector decoder is on the roadmap. The heavier binary and cryptographic parsers ship after the core text and token decoders — all of which are already live and working.

Browse the live decoders

Input is processed on your device. Nothing you paste is sent anywhere.

What is the TrueType / OpenType Inspector?

A font inspector parses the SFNT table directory of a TrueType or OpenType font file, listing its tables and decoding the metadata they hold — family and style names, glyph count, units per em and embedding permissions.

TrueType and OpenType share the SFNT container: a header, a table directory, then the tables themselves, each identified by a four-character tag. The essential ones are head (global metrics and units per em), name (all the human-readable strings), cmap (the character-to-glyph mapping), glyf or CFF (the outlines themselves, the difference between TrueType and PostScript-flavoured OpenType), and OS/2, which carries the fsType embedding permission bits.

Those two facts — what the cmap covers and what fsType permits — answer the questions that actually come up. A missing glyph is a cmap coverage problem, not a rendering bug. And fsType tells you whether a font may legally be embedded in a PDF or served on the web, which is a licensing question with real consequences.

Advanced typography lives in GSUB and GPOS: ligatures, kerning, alternates, contextual substitutions. Their presence tells you whether a font supports the features a design depends on.

TrueType / OpenType Inspector at a glance

Container: SFNT — table directory of 4-character tags
Outlines: glyf (TrueType quadratic) or CFF (PostScript cubic)
Coverage: cmap table maps characters to glyphs
Licensing: OS/2 fsType bits set embedding permissions

How to use the TrueType / OpenType Inspector

1Load the .ttf, .otf or .woff file — it is parsed locally.
2Review the table list and the decoded name records.
3Check the cmap coverage and the fsType embedding permission bits.

When you would reach for it

Working out why a specific character renders as a fallback box.
Checking whether a font's licence permits web or PDF embedding.
Confirming a font has the OpenType features a design requires.

TrueType / OpenType Inspector — frequently asked questions

Last reviewed 25 July 2026 · questions or corrections: contact@decoder.tools