DTL OTMaster is a tool for cracking open and looking inside OpenType fonts (or plain old Windows TrueType fonts). It shows a fairly literal/direct representation of what?s in the various tables and subtables. It has an unobtrusive interface and allows direct editing of various fields. Why would I use OTMaster instead of FontLab Studio 5? FLS is a great program which I use a lot, but it interprets the OpenType font into its own internal format. It can?t open a font, make a tiny change and re-save it as a font without potentially changing other things... So tools like DTL OTMaster are really handy for that, because they show the unvarnished truth of what?s in the font, without interpretation.
Thomas Phinney, Phinney on Fonts
DTL OTMaster is a diagnostic tool, and it lets you do surgery. I sometimes need to perform post-production operations on font data, because in my workflow, the OpenType font file (.otf or .ttf) becomes the source format for OpenType Layout and hinting work. But even if one has a workflow in which a program like FontLab Studio remains the source format throughout, up to the point of final font generation, OTMaster is useful as a means of examining generated fonts, quality assurance.
John Hudson, Type designer and partner at Tiro Typeworks
As someone who works with OpenType fonts on an every-day basis, and with the tools that are used to build and check them, I would like to state here that DTL OTMaster is a fabulous tool. The best way for me to characterize it is that it gives me the power of some existing command-line tools, wrapped up in nice GUI. It handles CJK fonts well, including those with a large number of glyphs. I especially appreciate that there is a Mac OS X version.
Dr. Ken Lunde, Sr. Computer Scientist at Adobe Systems