⚙️

System Files

94 extensions

dll

.dll

Dynamic Link Library

bin

.bin

Binary File

deb

.deb

Debian Software Package

rpm

.rpm

Red Hat Package Manager

aes

.aes

Advanced Encryption Standard

000

.000

Generic Data File

111

.111

Binary File

509

.509

PKCS#7 Certificate (often .P7B or .P7C)

7ini

.7ini

7-Zip Configuration File

acf

.acf

Adobe Color File

acroplugin

.acroplugin

Adobe Acrobat Plugin

add

.add

AddIn, Office Add-in

addin

.addin

Add-In

aepkey

.aepkey

Adobe After Effects Keyframe File

afs3

.afs3

Android File System v3

0

.0

Unknown

0cc

.0cc

0CC Core Configuration File

103

.103

Unknown File Type

104

.104

Unknown File

106

.106

Unidentified File

10o

.10o

10-Digit Octal Number

114

.114

Unknown or Obscure File

129

.129

Unknown Format / Custom Data

131

.131

Unidentified File

132

.132

Unknown or Proprietary Binary Data

136

.136

Unknown or Generic Binary Data

141

.141

Unknown or Rare File Format

146

.146

Unknown Format (Potentially Proprietary or Obsolete)

153

.153

Unrecognized File Format

156

.156

HP 156 Laser Printer Driver

157

.157

Unknown

159

.159

Unusual or Obscure File

15u

.15u

Unknown or Obscure Format

167

.167

Unknown or proprietary format

168

.168

Generic Data File

17

.17

NCSA Mosaic Configuration File

172

.172

Generic Binary Data File

18

.18

Unknown or Obscure Format

19

.19

Unconfirmed or Obscure File

193

.193

Unknown File Type

198

.198

Protexis License Protocol File

199

.199

Unknown Format / Obsolete

202

.202

Generic Binary Data File

209

.209

Internal Configuration Data

219

.219

Uncommon, likely proprietary or custom data container

235

.235

Unknown or Obsolete Format

323

.323

Microsoft NetMeeting / Internet Locator Service File

34

.34

Unknown Format / Generic Data

3fs

.3fs

3F Software File

3~6

.3~6

Uncommon temporary file

4ui

.4ui

4UI User Interface Resource

5

.5

Unknown Format

697

.697

Unknown or Obscure File Format

73l

.73l

7-Zip Log File

73u

.73u

Unknown or Obscure Format

86i

.86i

Epson 86i Printer Driver File

890

.890

Generic Data File

8bdt

.8bdt

8bitdo Device Tree

999

.999

Possibly a placeholder or custom file format

a01

.a01

Data file (often backup or archive)

a2menu

.a2menu

Amiga 2000 Menu File

a2panel

.a2panel

A2 Panel Configuration File

aaui

.aaui

Autodesk Alias UI Layout

aawdef

.aawdef

Adobe Animate Workspace Definition

abg

.abg

ActiveBuilder Gateway

abk

.abk

ABK File / Arcabit Antivirus Database

abn

.abn

Adobe Binary

accessor

.accessor

Accessor File

aclock

.aclock

Apple Animation Clock Data

acs2

.acs2

Adobe Color Settings File

acs3

.acs3

Autodesk Content Service File

adiumemoticonset

.adiumemoticonset

Adium Emoticon Set

adiumlistlayout

.adiumlistlayout

Adium List Layout File

adiumlisttheme

.adiumlisttheme

Adium Theme List File

adiummessagestyle

.adiummessagestyle

Adium Message Style

adiumplugin

.adiumplugin

Adium Message Style Plugin

adm

.adm

Active Directory Management (and others)

adml

.adml

Application Description Meta Language

admx

.admx

Administrative Template XML

adox

.adox

Active Directory Object Schema

aeu

.aeu

Acoustic Echo Cancellation Unit

afc

.afc

Apple Application Support File

afploc

.afploc

Apple Location File

afs

.afs

Andrew File System

agent

.agent

Agent File

agprefs

.agprefs

Acorn Preferences File

ahc

.ahc

ActiveHole Cache File

ahl

.ahl

Android Hotswap Layout

125

.125

Unknown Format

126

.126

Not commonly associated with a specific standard file format

155

.155

Uncommon or Obscure Data File

2

.2

Unknown or Generic Binary File

89u

.89u

Unknown Format

8u

.8u

Unknown/Proprietary Format