DTL OTMaster is a technical OpenType font editor developed by Dutch Type Library and URW Type Foundry. With OTMaster, you can inspect, troubleshoot and modify OpenType and TrueType fonts in a non-invasive way — in all their flavors, including variable fonts, color fonts, TTC collections, WOFF2 web fonts and CID-keyed OTF fonts.
With OTMaster’s Glyph Editor, you can import a monochrome EPS or SVG drawing, ornament or logo, and add it as a new glyph or replace an existing glyph in a font.
The new version 7.9 lets you test OpenType Font Variations, view and change OpenType Layout features, edit low-level OpenType font tables, and fix bugs or problems.
When you open an OTF or TTF file in FontLab VI or Fontographer, the font is converted into an internal format. You can then perform large and small modifications. When you export the font, the font is completely rebuilt, so some of the original data may be modified, updated or discarded.
OTMaster is different: it does not perform any conversion but lets you examine the internal structures of the binary font, and perform small targeted modifications of some portions of the font without even touching the other parts.
Each OpenType font file consists of a collection of tables — binary data structures identified by four-character names such as head, name, GSUB, GPOS, or glyf. OTMaster reveals the contents of any OpenType font table in a Nested Tables view or in a Text Dump view.
Open any OTF, TTF or TTC font file, or import a WOFF2 or WOFF file, then navigate and examine the contents of any OpenType font in OTMaster. Refer to the OpenType and TrueType specifications for detailed explanation about each font table — it’s an excellent way to learn the structure of the OpenType fonts, and to become familiar with how fonts work.
In the Nested Tables view, you can edit most fields inside the font tables. You can also view and export the contents of each font table as a plain-text or XML file. Use the Table Comparator to check and edit various OpenType table fields across many fonts.
Use Consistency Checker to check which scripts and languages your font covers, and to automatically detect and correct family-linking, linespacing (vertical metrics) or encoding (Unicode range and codepage coverage) problems.
Use the new Proofing Tool to print or export to PDF all or selected glyphs (one or multiple per page) of the current or all open fonts, or specimens with custom text. Show, hide or customize the outline, points, glyph and font metrics, labels and other details.
Font Variations is an extension of the OpenType font format that allows fonts to change their weight, width and other aspects of appearance on the fly. OTMaster 7.9 supports variable fonts in both TrueType and CFF2 flavors. You can explore the variation tables (fvar, STAT, HVAR, MVAR, avar, cvar, gvar, CFF2) and edit most of them.
Use the new Font Variation Viewer to preview a variation instance in the Text Viewer or the glyph map. Pick a predefined instance from a list or use sliders to choose an arbitrary instance. Save an arbitrary instance as a predefined instance and edit existing instances. Use the improved Side by Side Viewer to compare glyphs and predefined instances from all open fonts.
OpenType fonts can include font features that substitute and precisely position glyphs. This allows for correct typographic rendering of Arabic or Indic text, for automatic small caps, swashes, ligatures, as well as stacking diacritical marks and cursive attachment. Use the Text Viewer to test your font rendering and OpenType features on longer text strings, including texts in complex scripts such as Arabic or Devanagari.
Use the GPOS/GSUB Table Viewer to perform a detailed visual analysis of all OpenType Layout substitutions in the font’s GSUB table, or to check and edit OpenType kerning and mark positioning in the GPOS table. Edit the mark positioning visually (drag the mark, Shift+drag for horizontal adjustment, Shift+Alt+drag for vertical adjustment), or use the numeric fields to edit any GPOS adjustment, including kerning. Edit legacy TrueType kerning with the kern table Viewer.
Export and import OpenType feature definitions in FEA format. When OTMaster imports feature definitions in the FEA format, it intelligently subsets them to match the font’s glyph set, so you can develop a large FEA file that defines features for many writing systems and import it into a smaller font. Import the exported FEA file into FontLab VI’s Features panel.
Use OTMaster’s Glyph Editor to add or modify a glyph in an non-invasive manner: all of the font’s naming, hinting, kerning and OpenType Layout features will be intact — just as if you were using a high-precision surgical laser knife.
Export a glyph into EPS or SVG, edit it in another app and import it back into the font. This allows you to add an extra symbol such as an ornament or a logo into the font without a potentially complex process of rebuilding the font from its sources.
Use the Glyph Copy Tool to copy a glyph from one font to another. Use the Text Viewer or the Glyph Editor to edit the glyph metrics (advance widths). OTMaster’s glyph editing, spacing and copying is a good choice if you only need to change one or a few glyphs — for larger modifications, use FontLab VI.
Together with FontLab VI, OTMaster forms an integrated type design and font development workflow. Draw, space, kern, hint and test your fonts or font families in FontLab VI. Export the fonts into monochrome, variable or color OpenType formats. Then use OTMaster to examine the results, produce test printouts, make last-minute modifications or produce customized font versions for individual clients.