Frequently Asked Questions
Common issues and practical answers based on current behavior.
Which formats can I import for glyph browsing?
Import TTF, OTF (CFF/CFF2), WOFF, WOFF2, TTC, and OTC. For a collection, select one face to preview and subset. Variable and color fonts are supported; color rendering depends on the format and macOS version.
Can WebFont create icon fonts from SVG files?
Yes. Use Font Builder to import outlined SVG artwork, assign glyph names and Unicode values, and export TTF, WOFF, WOFF2, or a complete web package with CSS, demo HTML, and metadata.json.
Can I edit an existing font?
Font Builder can import a static TrueType-based source font, add new SVG glyphs, or replace existing Unicode glyphs. Replacement glyph IDs are kept stable when editing a source font.
What is a .webfontproject file?
It is a project package for Font Builder. It saves the current SVG glyphs, build settings, output options, replacement targets, and embedded source font data when a source font is used.
Why does Font Builder reject some SVG files?
Font Builder expects outlined static SVG artwork. Unsupported SVG features such as live text, raster images, masks, filters, clipping, scripts, animation, and external resources are rejected instead of being silently changed.
What does Preflight Check inspect?
Preflight Check reports Unicode conflicts, duplicate glyph names, empty paths, abnormal SVG dimensions, baseline/ascender/descender issues, unsupported SVG features, and glyphs that may be too complex for stable font output.
Do Preflight errors block building?
Preflight is a warning and review step. You can build passing glyphs to skip red rows, or continue with all glyphs if you want the native engine to try them. The build engine may still reject unsupported or unsafe input during export.
Can WebFont turn text into SVG?
Yes. Text to SVG converts words, phrases, and multi-line text into SVG outlines using the loaded font. It supports font size, every variable axis the font exposes, letter spacing, line height, wrap width, alignment, padding, fill color, and fallback controls. Supported vector color glyphs keep their colors, bitmap color glyphs are embedded as PNG, and the fill color applies to monochrome artwork.
Why did my existing glyph list disappear after importing another file?
Import currently replaces the active session data. If you need comparison, open another workspace window and load a different font there.
Why can I not generate a subset from multiple loaded fonts?
Generate a subset from one source font or one selected TTC/OTC face at a time. Collection import does not merge its faces into one output.
Which subset outputs are supported?
Export WOFF2, WOFF, or TTF / OTF (original outlines). TrueType and bitmap sources produce .ttf; CFF/CFF2 sources produce .otf. Subsets retain the selected glyphs and required dependencies, preserve variable axes and supported color resources, and offer OpenType layout and feature-tag controls. This does not convert outlines. For variable fonts, the Export panel's Variable Font section keeps all axes or bakes a static instance into the subset and web package outputs.
Why does subset generation fail on some fonts?
Subsetting supports TrueType, CFF/CFF2, variable, and color fonts. Invalid input, unsupported structures, or failed output validation can still block export.
Some AAT/Graphite layouts retain all original glyph data to keep references valid. Shared SVG or legacy bitmap resources may also be preserved intact, so size reduction can be limited. Unsupported private tables may be dropped, and JSTF is removed with a warning. Review the export warnings for the specific font.
Which formats are supported in Format Conversion? Can it convert between TTF and OTF?
Yes. Use explicit TTF or OTF targets to convert supported static TrueType and CFF fonts in either direction, including decoded WOFF/WOFF2 inputs. Supported variable TrueType (glyf/gvar) and CFF2 fonts can also be converted between outline types when they meet the variation limits. Choose TTF/OTF (original outlines) to preserve the existing outline type instead.
TrueType-to-CFF conversion elevates quadratic curves to cubic curves; CFF-to-TrueType conversion approximates cubic curves with quadratic curves. Both remove original hinting and can change file size and small-size rendering. Variable conversion requires 1–16 axes, at most 48 outline variation regions, compatible master contours, and solvable variation data; CFF2 output can grow substantially. Cross-outline conversion rejects bitmap color fonts (sbix/CBDT/EBDT), VARC, CFF1 with axes, CFF2 without fvar, and incompatible layout data. Web-font packaging and unpacking preserve the source outline type and are separate operations.
Supported conversion matrix:
| Source Format | Target Option | Actual Output | Status | Outline & Conversion Details |
|---|---|---|---|---|
| TTF | WOFF / WOFF2 | .woff / .woff2 | Supported | Packages TrueType outlines as a web font without changing the outline type |
| OTF (CFF/CFF2) | WOFF / WOFF2 | .woff / .woff2 | Supported | Packages CFF/CFF2 outlines as a web font without changing the outline type |
| WOFF / WOFF2 | TTF/OTF (original outlines) | .ttf | Supported | Restores TrueType outlines as .ttf without cross-conversion |
| WOFF / WOFF2 | TTF/OTF (original outlines) | .otf | Supported | Restores CFF/CFF2 outlines as .otf without cross-conversion |
| TTF | OTF (CFF) | .otf | Supported (static fonts) | Static TrueType → CFF: elevates quadratic curves to cubic curves; removes original hinting |
| OTF (CFF) | TTF | .ttf | Supported (static fonts) | Static CFF → TrueType: approximates cubic curves with quadratic curves; removes original hinting |
| Variable TrueType ↔ CFF2 | TTF / OTF | .ttf / .otf | Supported with limits | Preserves all axes and supported color data; requires 1–16 axes, at most 48 outline variation regions, compatible masters, and solvable variation data; CFF2 output can be much larger |
| Bitmap color (sbix/CBDT/EBDT), VARC, CFF1 with axes, CFF2 without fvar | Outline conversion | — | Not supported | Does not turn bitmap artwork into vector outlines; use original-outline export or web packaging to keep the source data |
When converting WOFF/WOFF2 to desktop font, why does it export .ttf sometimes and .otf other times?
With TTF/OTF (original outlines), the output extension follows the outlines inside the WOFF/WOFF2 container: TrueType produces .ttf; CFF/CFF2 produces .otf. Select explicit TTF or OTF only when you want that outline format and the source meets the cross-conversion requirements.
What does “Generate Web Package” produce?
It generates a package folder with:
fonts/(WOFF2+WOFF)- one CSS file (
@font-face,unicode-range) demo.htmlpreview page
Font Builder can also generate a web package with font files, CSS, demo HTML, metadata, glyph previews, and HTML snippets for icon-font usage.
Are variable fonts supported?
The inspector detects variable fonts, and Text to SVG exposes every axis the loaded font provides. Subsets preserve the font's variable axes and variation data; web-font packaging keeps the original outline type. The Export panel's Variable Font section can keep all axes or bake a static instance into Font Subset and Web Package outputs. Supported variable TrueType ↔ CFF2 outline conversion is available with the limits listed above.
Can imported color glyphs be previewed and exported in color?
Yes. The glyph grid and enlarged preview render supported color glyphs in their original colors. Single and batch PNG/PDF exports preserve those colors. Core Text handles supported COLR/CPAL, sbix, and embedded SVG glyphs; the built-in bitmap reader can display CBDT PNG glyphs even when macOS cannot load the font directly. System rendering support varies by macOS version.
Color SVG export embeds a transparent-background PNG at the selected export resolution. It preserves appearance, but is not an editable vector outline or an outlined SVG input for Font Builder. Ordinary monochrome outline SVG export remains vector. Color support in subsetting does not enable cross-outline conversion of color fonts.
Why do I see warnings after generation?
Warnings come from built-in validation checks (for example missing cmap mappings, size regressions, or OpenType layout table consistency checks). Outputs may still be written when only warnings are present.
Does WebFont upload my font files?
No. Font processing is local. See the privacy page for details.