DB Master is a powerful and flexible database for early personal computers. It was produced by Stoneware Inc., and in 1986 it switched ownership to Macon Software Inc.

Ashton-Tate dBase was an early popular database management system for CP/M and MS-DOS. It was regarded as one of the killer applications for CP/M, and achieved good success. At the time of conception Ashton-Tate was a garage based company but quickly grew.

Decision Pad, from Apian Software, is a decision support tool that uses a decision matrix approach. It also supports a three-dimensional decision matrix for group decisions, and can import/export data from Lotus 1-2-3 files. It competed against a similar tool called "Prism".

DECTalk was a text to speech system used in automated telephone, radio, and TV systems. It was notably used as an artificial voice by Stephen Hawking. Most DECTalk devices were standalone serial devices, however DEC did produce an ISA expansion card for the IBM PC that contained this functionality. This software is required to operate these ISA cards.

DeluxePaint, from Electronic Arts, is a bitmap pixel graphics editor that was ported to DOS from the Amiga.

DeluxePaint Animation is a raster based animation program based on the DeluxePaint painting program. It features ease of use, powerful drawing functionality, and a playback utility. As a DOS program, it was limited to 640k and 320x200 resolution in 256 colors.

Derive was a computer algebra and graphing system, developed as a successor to muMATH by Soft Warehouse, Inc. in Honolulu, Hawaii, now owned by Texas Instruments. Derive was implemented in muLISP, also by Soft Warehouse. The first release was in 1988 for DOS. It was discontinued on June 29, 2007 in favor of the TI-Nspire CAS. The last and final version is Derive 6.1 for Windows.

DesignCAD is a low end, but well featured, drafting program. It was sometime a companion product to DesignCAD 3D.

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

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.

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.

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.

Disney Animation Studio is an animation graphics tool, that originated on the Amiga. It supports multiple VGA resolutions.

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. This software was often bundled with modems or PCs. It was often accompanied by Delrina WinFax.

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.

DR Draw is a shape-based drawing program that uses Digital Research's GSX graphics library, making it portable across CP/M and DOS architectures with different video systems.