ftvalid - Man Page

font layout table validator


ftvalid [options] fontfile


ftvalid is an OpenType layout table validator.

This program is part of the FreeType demos package.


-f index

Select font index (default: 0).

-t validator

Select validator. Available validators are ot, gx, and ckern.

Note that the availability of validators depends on compile-time options of FreeType (this is, whether the modules `otvalid' and `gxvalid' are compiled into the library).

-T tbls

[ot, gx] Select sfnt table name tags to be validated. Use `:' to separate tags.

Supported tables in ot validator are BASE, GDEF, GPOS, GSUB, JSTF, and MATH.

Supported tables in gx validator are feat, mort, morx, bsln, just, kern, opbd, trak, prop, and lcar.

Example: -T "feat:morx"

-T dialect

[ckern] Select classic kern dialect for validation. Use `:' to separate dialect names. If more than one dialect is specified, all dialects are accepted when validating.

Supported dialects in ckern validator are ms and apple.


List the layout-related SFNT tables available in the font file. The selected validator (with option -t) affects the list.

ckern is applicable to `kern' table only. Option -L lists dialects supported in ckern validator only if `kern' table is available in the font file.

-V level

Validation level. Possible values are 0 (default), 1 (tight), and 2 (paranoid).


Show version.

Environment Variables


You can specify `component:level' pairs for tracing. level must be in the range [1,7].

Available components for ot validator are otvmodule, otvcommon, otvbase, otvgdef, otvgpos, otvgsub, and otvjstf.

Available components for gx validator are gxvmodule, gxvcommon, gxvfeat, gxvmort, gxvmorx, gxvbsln, gxvjust, gxvkern, gxvopbd, gxvtrak, gxvprop, and gxvlcar.

Available component for ckern validator is gxvkern only.

Example: FT2_DEBUG="otvcommon:5 gxvkern:7"

FT2_DEBUG only works if tracing support is compiled into FreeType.


October 2020 FreeType 2.10.4