DesignCAD is a low end, but well featured, drafting program. It was a companion product to DesignCAD 3D. In many cases, the "2D" version would be preferable for creating 2D designs, which could then be directly imported and modeled further in DesignCAD 3D. DesignCAD 2D remained a separate product until DesignCAD 97.

DesignCAD 3D is a powerful, easy to use, and low cost DOS based CAD program that claimed to have all of the features of the more expensive CAD programs. It competed against low-cost CAD programs such as TurboCAD, Generic CADD, and Drafix. It was sometimes sold alongside DesignCAD 2D

DesignView is a 2d drawing and CAD program, designed to functionally refine smaller components for use in larger CAD drawings. It was praised for its ability to include rules and programmatic manipulation rather than just being a drawing program. DesignView features equation solving, mass property synthesis, user defined functions, and animation. Supports reading Autocad, Versacad, and Cadkey files.

DevTech's Deskman/2 is a set of desktop and system management tools for OS/2. It contains data compression tools, networking tools, performance monitoring tools, and desktop management tools.

DESQView, from Quarterdeck, was a DOS application multi-tasker and in later versions functioned as an X client for applications on remote UNIX systems. It competed against IBM Topview. The original DESQ was just a task switcher, but subsequent versions offered preemptive multitasking of well behaved DOS programs on real-mode 8088 PCs. It gained popularity when DESQView 386 added virtual x86 support. This enabled the ability to multi task many poorly behaved programs, and was often used on BBSes due to its excellent COM port handling. It was later overtaken by OS/2 and Windows.

Diagram-Master, from Decision Resources and later Ashton-Tate, is a graphics tool specifically geared toward making organization and Gantt charts. It can produce very high-quality presentation graphics using laser printers and plotters. Supports CGA, EGA, and the IBM Professional Display. This program was also bundled in the Master Graphics Presentation Pack.

Diagraph, from Computer Support Corporation, is a program that lets users assemble presentations, charts, and graphs from a very large library of predefined symbols.

Released in 1997 by DayBreak Software, Break A Day is a calendar that shows a different Dilbert comic every day. Includes a 16-bit Windows 3.1 version, 32-bit Windows 9x/NT version, and a Mac version.

Direct Access is an easy to use menuing program designed to simplify access to applications on systems with many programs loaded on the hard drive. It is customizable, includes screen blanking, and includes password protection and usage logging. Later versions also detect common programs already installed on the hard disk.

Disk Technician, from Prime Solutions Inc., is a hard disk utility and surface monitor. It contains an interleave adjuster and pattern tester similar to Spinrite. The Gold version also includes a defragmenter and disk-level virus protection.

This is a low-end spreadsheet program from Disk-Count software, a vendor notable for their budget software titles. "This program is designed for the first time user with the capability for more advanced users. A spreadsheet is ideal for calculating any set of numbers that you normally would do by hand. Some of the uses are for preparing home budgets, calculating financial payments, tracking car expenses, and creating statistical models."

DiskClone, from Quarterdeck, is a simple, professional, small, powerful, and easy to use hard disk cloning tool. It can copy a drive to another internal or external drive of different sizes. It can be used as a backup, or a migration tool to a new drive. It all fits on a single floppy disk. "Corporate" editions.

DiskDoubler is an automated file compression program for the Apple Macintosh. It does not compress the entire drive, but rather specified files. It automatically compresses and recompresses files as you use them.

Diskeeper is a professional disk defragmenting tool with versions for both 9x and NT. It includes features such as scheduling and background defragmentation.

Diskette Filing System is a small, inexpensive "budget-oriented" program that keeps track of the contents of your floppy disks.

Diskette Manager, from BLOC publishing, previously from Lassen Software, is a software tool for the IBM PC and Tandy that inventories the contents of your floppy disks in to a database. It enables you to quickly and easily search for files or print disk labels.

DiskLock, From Fifth Generation Systems, and later from Symantec as Norton DiskLock, is a data security tool that can lock a hard disk or individual files or directories so that it requires a password to access any data. It can also log activity to detect unauthorized access attempts. It also features the ability to lock the system after an idle usage period. There were versions for PC and Mac.

DiskTop is a desk accessory intended for MacOS 6 that lets you perform file management and search files without having to exit the program you are running. In MacOS prior to version 7, you could only use one application at a time. You would have to exit your application in order to return to the Finder desktop. However Desk Accessories are always available to all running programs, so DiskTop works around this limitation by making file management part of a Desk Accessory.

Disney Animation Studio is an animation graphics tool, that was first released in 1990 on the Amiga. It mimics the process of traditional hand drawn animation, including the ability to see previous frames under the current frame. It was intended as more of a fun educational title, and lacks the capabilities of a serious drawing tool. It supports multiple VGA resolutions and Sound Blaster sound.

DisplayWrite is a word processor that is based on the IBM Displaywriter dedicated word processing system. It directly competed with software ports of dedicated word processors such as the Wang Word Processing System (or its clone MultiMate ), Lanier Word Processing Software, Xerox, DEC, or similar.

Delrina DosFax is a DOS based program for sending and receiving faxes via a modem that has fax capabilities. Notably, it includes a TSR to capture and send directly from within DOS applications. This software was often bundled with modems or PCs. It was often accompanied by Delrina WinFax.

Helix, first released in 1984, and later Double Helix, is an easy to use relational database for the Apple Macintosh. It was among the earliest serious database product for the Apple Macintosh, and gained a strong following. It features a visual programming system, database building through point-and-click operations, and options for multiuser over AppleTalk.

First released in 1989, DoubleDisk was the first real-time drive compression product for DOS. It is a fairly no-frills program and sticks to what it does best. It was relatively low cost compared to its later competitors. and Expandz! Plus

DoubleDOS is a simple and easy to use multitasking tool for DOS. It can preemptively run up to two DOS programs at a time. Its main advantage is that it requires very little RAM overhead compared to other multitasking or task switching environments. Because DOS programs can and usually do bypass OS calls, many programs must be "patched" in order to work. things at once, then this would have been a good choice. Reportedly, the first version may have worked with DOS 1.x.

DoubleTools is a set of Windows-based utilities that adds functionality to DoubleSpace, included with MS-DOS 6.0.