Licensing and embedding permissions
Converting a font is a technical operation on a file. It creates no rights. If you were not permitted to embed, subset or redistribute a font before you converted it, you are not permitted to afterwards — and the fact that a tool let you do it is not a defence anyone has ever won with.
What the fsType bits say
Every OpenType font carries a 16-bit fsType field in its OS/2 table. The low four bits express one permission level: installable embedding, restricted licence embedding, preview and print embedding, or editable embedding. Bit 8 independently forbids subsetting. Bit 9 restricts embedding to bitmaps only.
The inspector decodes all of these and shows them beside the font's own copyright and licence strings. A font marked Restricted License Embedding should not be deployed on a website without written permission, regardless of format.
These bits were designed for document embedding in the 1990s and many foundries set them carelessly. Installable does not mean "licensed for the web". The licence text governs; the bits are a hint.
The common traps
Free for personal use. Extremely common on font aggregator sites, and it does not include your company's marketing site or your client's app. A desktop licence rarely includes web embedding.
Web fonts are usually licensed by monthly page views or by domain. Converting a self-hosted desktop font to WOFF2 to avoid a web licence is the exact scenario those licences exist to cover.
Bundled system fonts — the ones that came with your operating system or design tool — are almost never licensed for redistribution or self-hosting.
Subsetting is treated as modification by some licences and is separately forbidden by fsType bit 8 in others. Check both.
Fonts you can use freely
Fonts under the SIL Open Font License permit conversion, subsetting, web embedding and redistribution, subject to keeping the licence with the font and not selling it on its own. The reserved-font-name clause means a modified version must be renamed.
Apache 2.0 and public-domain fonts are similarly permissive. If in doubt, the licence text is usually in the font's own name table — the inspector shows it.
What Glyph Batch does about it
It shows the rights notice beside every file picker, decodes the fsType bits, surfaces the copyright and licence strings from the font itself, preserves those strings through every conversion and verifies they survived, and refuses by default to subset a font whose vendor forbade it.
It does not give legal advice, and none of the above is legal advice.
Related
Inspector
Read everything inside a font file in your browser: family and PostScript names, version, copyright and licence text, OS/2 embedding permissions, variation axes, colour tables and the full table directory.
OpenSubsetter
Subset fonts in your browser with HarfBuzz hb-subset. Keep pasted text, whole Unicode blocks or standard web ranges. Layout closure is preserved and licence strings are kept.
OpenPrivacy
Glyph Batch processes fonts entirely in your browser. No file is uploaded, no font name or metadata is recorded, and the Content-Security-Policy enforces it.
Open