SFD to CID Converter

SFD (SplineFont Database) is the native source file format of FontForge, the free and open-source font editor originally created by George Williams in 2000 under the name PfaEdit. The format stores a complete font project — glyph outlines (cubic and quadratic splines), advance widths, side bearings, hinting instructions, kerning and OpenType feature tables, naming records, and metadata — in a single human-readable text file. Each glyph is described by its Unicode code point, outline coordinates, reference composites, and anchors, making the entire font design inspectable and diffable with standard text tools. SFD functions as the editable working format during font development, from which finished fonts are compiled to binary formats like OTF, TTF, or WOFF. A primary advantage is version control friendliness — because SFD is plain text, font designers can track changes to individual glyphs, merge contributions from collaborators, and maintain full revision history using Git or any other VCS. The format's completeness is another strength: it preserves every piece of data that FontForge can represent, including TrueType instructions, contextual substitution lookups, and multiple master axes, avoiding round-trip data loss during editing. The SFD specification is publicly documented and has evolved through several versions. FontForge's widespread adoption in the open-source type design community means SFD serves as the source format for hundreds of freely licensed font families distributed worldwide.