FontTools

FontTools is a library for manipulating fonts, written in Python. Originally created by Just van Rossum (the creator of Python's original font tools) and now maintained by Behdad Esfahbod and the Google Fonts team, FontTools is the de facto standard library for font engineering in Python, with over 4,200 stars on its repository as of 2026. FontTools provides comprehensive support for reading, writing, and transforming OpenType, TrueType, PostScript, and WOFF/WOFF2 font formats. Key features include: full OpenType table support (reading and writing all OpenType tables including glyf, CFF, CFF2, gvar for variable fonts, GPOS for positioning, GSUB for substitution, name, cmap, hmtx, vmtx, and over 100 other tables), TrueType curve support (quadratic Bezier curves in glyf table with contour extraction, scaling, and transformation), PostScript CFF support (cubic Bezier curves in Compact Font Format with charstring parsing and subroutinization), variable font support (reading and generating OpenType variable fonts with designspace axes, instances, and variation deltas via the variationLib module), font merging and subsetting (combining fonts or reducing font file size by including only specified glyphs via pyftsubset), font inspection and comparison tools (ttx for converting between binary font format and XML, pyftinspect for detailed font analysis), ttx round-tripping (converting any binary font to an editable XML representation and back without loss), and integration with the broader Python font ecosystem (used by fontmake, afdko, and the Google Fonts pipeline for producing over 1,500 open-source font families).