Dabbler 
0013058-6239

Daisy Quest 1.0
DQ 1255

DataDesk 5.0
Tip:
Accepts any hex number between 1 and FFFFFFFF (inclusive) as a SN.

Datebook Pro and TouchBase Pro 
xxR79J4Y6J257ZM5
xxLA974R6J29IH0T
xx8S9Z4C6-2IO9O0
xxKM9K4Y6V2P-LBM
xxI59X46632TUJHG
xx2N9Q4J6B2ODOHI
76R79J4Y6J257ZM5
93LA974R6J29IH0T
658S9Z4C6-2IO9O0
87-792466D2S-2J3
45VG9C4O6C2ZA100
38WM9Y4Z672OHI4M

Daymaker 3.0.3
0148D-0F68F9-1F100
0349-13D8B8-F5000
03409-13D8B8-F5000

dBase IV 5.5
1234567-28

Death Blade
1.x
EZFMDTPG  'Anonymous'

Death Blade 1.x
EZFMDTPG
'ANONYMOUS'
EZFMDTPG
'Anonymous'
EJKALRMB
'Bill Gates'
YTFDCDYQ
'Doom'
FKFSTXDB
'Microsoft'

DeBabelizer 1.6.x
-9980-700087-963639
-4540-609699-575364
-4010-503318-842332
-0529-328819-739202
-0557-322478-973200
-0598-325148-856201
-1560-331589-612212
-1603-313250-595213
-1633-326920-478214

Deck II 2.5
33025-0008-1201-46401

Deliverance 1.0
51244-442657-100016

Delta Graph Pro 4.0
MUE40-0326-1631366984

Delta Graph Pro 3.5.x
MUU35-0827-3837184026

DesignWorks 3.14
CVFC
X9AF
VA1J
X5KA
95TL

DeskPicture 4.0.x
(* is a wildcard character here)
PS**X12157DP*
PS**X72811DP*
PS**X60222DP*

DeskTape 3.0
061900004

DiagnoSYS 1.0
B102131444366

Digital Dead 
xxnnn5nnxnnnnY
Tip:
x = alpha char n = numeric char

Digital Input Noise Reduction DINR 1.0
yj9660mkk236

DigiTrax 1.2
ALS4312536
ALS4312135

DigiTrax 1.0
ALS4312135

Dilbert Screen Saver 
5180-6344-1654

Dimensions 2.0
DAW100R3100720-191
DAW200U3200000-109
DAW200U3200001-742
DAW200U3200002-375
DAW200U3200003-292

Director 5.0
DRM500-53375-57072-29379
DRM500-57179-17072-29377
DRM500-54076-47072-29376

Director 4.0.3
DM403-1799-3074-2073
DM403-3702-6075-3064
DM403-3745-9071-4064
DM403-5713-8178-0037

Disk Cafe 
DC000444B52
DC000796A32

Disk Express II 
JV103761
JE103744
JI103774
JV103735
JX103737
JX103763
JY103738
JZ103739

Disk Manager Mac 
190915

DiskDup 2.7
3 Spaces to register in the copies box.

DiskDup Pro 1.0.3
1641882382
1800012382
0537912382

DiskMaster 1.0
DMR100AAA00000043

DiskTools Collection 3.x.y
DTC-03xy-013515798
DTC-03xy-078005618
DTC-03xy-442515138

DiskTop 4.5.2
0065449
0065279

DiskTop 4.5.1
65279

DiskTop 4.5.2
0065449
0065279

DiskTracker 1.0.2
UKUYUSYOKE 'Anonymous'

DiskTracker 1.x.x
UKUYUSYOKE
'ANONYMOUS'
UKUYUSYOKE
'Anonymous'
AKAQYAUWWG
'Bill Gates'
CSMGIIEYSS
'Doom'
QGCEQAYIKA
'Microsoft'

Ditto 1.0
XXXXXXXX-XXXXXXXX (any numbers in this format)
83220223-90129867

DomeWars 1.x
LCjZ1jhdk2m8EZB7
Md1gdDXc1000Y00X
WKhRUa6yKirb3WGi

DOOM
Tip:
IDDQD: Invincibility
IDKFA: All Guns, Keys and Full Ammo
IDFA: All Guns, and Full Ammo (No Keys)
IDCLEV + n : Warps you to n (Note: if the level is below 10 then you must press zero before n )
IDDT: Give you more on the map (Can only be done on map)(Note: 3 stages of this Normal, All  Walls, All Walls and All Things)
IDCLIP: Go through walls (If you type it again it returns to normal)
IDMYPOS: Get your position (not very useful)

Double Helix 
DHMC180800011V30R1

DoubleScroll 2.1
11000*FT33$2931

Down to Business 
SSN719

Download Mechanic 1.6.x
B-08468468
B-38223571
B-52504682

Download Mechanic
1.6.3
BSPC555100

DragStrip 2.0.1
2RC-Z2D-AQA6

Dramatic Pro
2344-2344-ABCD-2344-2344-3U35

DropStuff (any version)
DLXI-885-718316

DropStuff /w Expander Enhancer 4.0.x
DRPX-849-600006
DRPE-544-051483
DRPM-521-083176