Data file extensions
Structured machine-readable files used by apps, APIs, and automation workflows.
Total extensions in this category: 153
Extensions in Data
Explore the most searched extensions in this category.
- .json
JavaScript Object Notation
JSON is a lightweight text format used for APIs, configuration files, and data exchange.
- .pkpass
Apple Wallet Pass
PKPASS files contain digital tickets, boarding passes, coupons, and loyalty cards for wallet apps.
- .dat
Data File
.dat files are generic data files that can contain various types of data, often used by specific applications.
- .ac
AC Data File
.AC files are specialized data files used in specific software environments, often requiring niche applications to access them.
- .cl
CL Data File
.CL most commonly refers to an XML “Simple-Filter” document used with SIP event notification filtering. It is essentially an XML file (media type: application/simple-filter+xml) that is often best opened with an XML-capable editor or viewer.
- .cu
CU Data File
.cu most commonly refers to an NVIDIA CUDA C/C++ source code file used for GPU programming. On many Linux systems it is also mapped to the MIME type application/cu-seeme, which can confuse file identification and “Open with” suggestions.
- .cw
CW Data File
.cw is a CU-Writer (Word Chula) document/data file format associated with the registered MIME type application/prs.cww. It is primarily intended for use with the CU-Writer word processor on Windows.
- .dl
DL Data File
.dl files are most commonly Datalog source files (text programs/rules) associated with the registered media type application/vnd.datalog. You typically open them with a text editor or a Datalog tool such as Soufflé.
- .dp
DP Data File
.dp files are most commonly OSGi Deployment Packages: standard JAR (ZIP) archives used to deploy/update software on OSGi-based systems.
- .dx
DX Data File
.DX is most commonly a JCAMP-DX spectroscopic data exchange file: an open, text-based format used to store and share spectra (for example IR, NMR, and MS). You can open it with JCAMP-DX viewers (such as JSpecView) or import it into scientific tools like MATLAB.
- .ep
EP Data File
.EP files are most commonly Bluetooth “Easy Pairing” (EP) out-of-band (OOB) data used with NFC-based Bluetooth pairing. They are typically consumed by Bluetooth/NFC tools and device stacks rather than opened like a document.
- .ez
EZ Data File
.ez files are most commonly Andrew Toolkit (AUIS/ATK) “EZ” documents (also called Andrew insets). They are typically opened with the Andrew/AUIS EZ editor or compatible Andrew Toolkit software.
- .fb
FB Data File
.fb is most commonly associated with Adobe FrameMaker/Maker-family documents and is often served with the non-standard MIME type application/x-maker. It typically requires FrameMaker-compatible software to open on desktop systems.
- .fm
FM Data File
.fm is most commonly an Adobe FrameMaker document file used for technical and structured documentation. You typically open it with Adobe FrameMaker on a desktop system.
- .fo
FO Data File
.FO most commonly refers to an XSL-FO (XSL Formatting Objects) XML document used to render paginated output like PDF via an FO processor. The same .fo extension is also used for Software602 602XML electronic forms, so you may need to identify which kind you have before choosing an app.
- .gf
GF Data File
.gf files are TeX/METAFONT “generic font” bitmap output files, typically converted to .pk for use by DVI/TeX tools. You usually open them with TeX utilities like gftype or convert them with gftopk.
- .h5
H5 Data File
.h5 is an HDF5 data file used to store large, structured datasets (arrays, tables, and metadata) in a single container. You can open it with HDF5 tools (HDFView, h5dump/h5ls) and many scientific/engineering applications such as MATLAB.
- .jt
JT Data File
.JT files are used for structured application data, imports/exports, and machine-readable workflows. Open with the originating app, text editors, or specialized data tools. This guide covers opening methods, troubleshooting, and security best practices. Common MIME type: model/JT.
- .le
LE Data File
.LE files are used for structured application data, imports/exports, and machine-readable workflows. Open with the originating app, text editors, or specialized data tools. This guide covers opening methods, troubleshooting, and security best practices. Common MIME type: application/vnd.bluetooth.le.oob.
- .ma
MA Data File
.MA files are used for structured application data, imports/exports, and machine-readable workflows. Open with the originating app, text editors, or specialized data tools. This guide covers opening methods, troubleshooting, and security best practices. Common MIME type: application/mathematica.
- .mb
MB Data File
.MB files are used for structured application data, imports/exports, and machine-readable workflows. Open with the originating app, text editors, or specialized data tools. This guide covers opening methods, troubleshooting, and security best practices. Common MIME type: application/mathematica.
- .me
ME Data File
.ME files are used for structured application data, imports/exports, and machine-readable workflows. Open with the originating app, text editors, or specialized data tools. This guide covers opening methods, troubleshooting, and security best practices. Common MIME type: application/x-troff-me.
- .mm
MM Data File
.MM files are used for structured application data, imports/exports, and machine-readable workflows. Open with the originating app, text editors, or specialized data tools. This guide covers opening methods, troubleshooting, and security best practices. Common MIME type: application/x-freemind.
- .ms
MS Data File
.MS files are used for structured application data, imports/exports, and machine-readable workflows. Open with the originating app, text editors, or specialized data tools. This guide covers opening methods, troubleshooting, and security best practices. Common MIME type: application/x-troff-ms.
- .nb
NB Data File
.NB files are used for structured application data, imports/exports, and machine-readable workflows. Open with the originating app, text editors, or specialized data tools. This guide covers opening methods, troubleshooting, and security best practices. Common MIME type: application/vnd.wolfram.mathematica.
- .nc
NC Data File
.NC files are data files commonly used for scientific data storage and can be opened with specialized software on various platforms.
- .nq
NQ Data File
.NQ files are used for structured application data, imports/exports, and machine-readable workflows. Open with the originating app, text editors, or specialized data tools. This guide covers opening methods, troubleshooting, and security best practices. Common MIME type: application/n-quads.
- .nt
NT Data File
.NT files are used for structured application data, imports/exports, and machine-readable workflows. Open with the originating app, text editors, or specialized data tools. This guide covers opening methods, troubleshooting, and security best practices. Common MIME type: application/n-triples.
- .cue
Cue Sheet File
CUE files are metadata files that describe the layout of tracks on a CD or DVD.
- .ob
OB Data File
.OB files are used for structured application data, imports/exports, and machine-readable workflows. Open with the originating app, text editors, or specialized data tools. This guide covers opening methods, troubleshooting, and security best practices. Common MIME type: application/vnd.1ob.
- .p8
P8 Data File
.P8 files are used for structured application data, imports/exports, and machine-readable workflows. Open with the originating app, text editors, or specialized data tools. This guide covers opening methods, troubleshooting, and security best practices. Common MIME type: application/pkcs8.
- .pk
PK Data File
.PK files are used for structured application data, imports/exports, and machine-readable workflows. Open with the originating app, text editors, or specialized data tools. This guide covers opening methods, troubleshooting, and security best practices. Common MIME type: application/x-tex-pk.
- .pt
PT Data File
.PT files are used for structured application data, imports/exports, and machine-readable workflows. Open with the originating app, text editors, or specialized data tools. This guide covers opening methods, troubleshooting, and security best practices. Common MIME type: application/vnd.snesdev-page-table.
- .rdc
RenderDoc Capture File
RDC files are used to store graphics rendering data captured by RenderDoc, a graphics debugger.
- .rd
RD Data File
.RD files are used for structured application data, imports/exports, and machine-readable workflows. Open with the originating app, text editors, or specialized data tools. This guide covers opening methods, troubleshooting, and security best practices. Common MIME type: chemical/x-mdl-rdfile.
- .rl
RL Data File
.RL files are used for structured application data, imports/exports, and machine-readable workflows. Open with the originating app, text editors, or specialized data tools. This guide covers opening methods, troubleshooting, and security best practices. Common MIME type: application/resource-lists+xml.
- .rq
RQ Data File
.RQ files are used for structured application data, imports/exports, and machine-readable workflows. Open with the originating app, text editors, or specialized data tools. This guide covers opening methods, troubleshooting, and security best practices. Common MIME type: application/sparql-query.
- .sc
SC Data File
.SC files are used for structured application data, imports/exports, and machine-readable workflows. Open with the originating app, text editors, or specialized data tools. This guide covers opening methods, troubleshooting, and security best practices. Common MIME type: application/vnd.ibm.secure-container.
- .sd
SD Data File
.SD files are used for structured application data, imports/exports, and machine-readable workflows. Open with the originating app, text editors, or specialized data tools. This guide covers opening methods, troubleshooting, and security best practices. Common MIME type: chemical/x-mdl-sdfile.
- .sm
SM Data File
.SM files are used for structured application data, imports/exports, and machine-readable workflows. Open with the originating app, text editors, or specialized data tools. This guide covers opening methods, troubleshooting, and security best practices. Common MIME type: application/vnd.stepmania.stepchart.
- .sr
SR Data File
.SR files are used for structured application data, imports/exports, and machine-readable workflows. Open with the originating app, text editors, or specialized data tools. This guide covers opening methods, troubleshooting, and security best practices. Common MIME type: application/vnd.sigrok.session.
- .st
ST Data File
.ST files are used for structured application data, imports/exports, and machine-readable workflows. Open with the originating app, text editors, or specialized data tools. This guide covers opening methods, troubleshooting, and security best practices. Common MIME type: application/vnd.sailingtracker.track.
- .ac2
AC2 Data File
.AC2 files are data files used by Banana Accounting for managing financial information, including transactions and budgets.
- .acc
ACC Data File
.ACC files are specialized data files used by specific applications, often related to security systems, and require compatible software to open.
- .acu
ACU Data File
.ACU files are compiled data files used by COBOL applications to execute code efficiently across platforms.
- .aep
AEP Data File
.AEP files are project files used by Adobe After Effects for creating motion graphics and visual effects.
- .afp
AFP Data File
.AFP files are specialized data files used primarily in high-volume printing and document management systems, supporting complex document layouts.
- .age
AGE Data File
.AGE files are specialized data files used in specific applications, requiring compatible software to open.
- .ait
AIT Data File
.AIT files are data files used primarily for storing application-specific information and can be opened with compatible software across various platforms.
- .alc
ALC Data File
.ALC files are specialized data files used by certain applications, often related to chemical data processing.
- .sw
SW Data File
.SW files are used for structured application data, imports/exports, and machine-readable workflows. Open with the originating app, text editors, or specialized data tools. This guide covers opening methods, troubleshooting, and security best practices. Common MIME type: chemical/x-swissprot.
- .uo
UO Data File
.UO files are used for structured application data, imports/exports, and machine-readable workflows. Open with the originating app, text editors, or specialized data tools. This guide covers opening methods, troubleshooting, and security best practices. Common MIME type: application/vnd.uoml+xml.
- .wg
WG Data File
.WG files are used for structured application data, imports/exports, and machine-readable workflows. Open with the originating app, text editors, or specialized data tools. This guide covers opening methods, troubleshooting, and security best practices. Common MIME type: application/vnd.pmi.widget.
- .wk
WK Data File
.WK files are used for structured application data, imports/exports, and machine-readable workflows. Open with the originating app, text editors, or specialized data tools. This guide covers opening methods, troubleshooting, and security best practices. Common MIME type: application/x-123.
- .wv
WV Data File
.WV files are used for structured application data, imports/exports, and machine-readable workflows. Open with the originating app, text editors, or specialized data tools. This guide covers opening methods, troubleshooting, and security best practices. Common MIME type: application/vnd.wv.csp+wbxml.
- .a2l
A2L Data File
.A2L files are data files used in automotive systems for calibration and measurement of ECUs.
- .ami
AMI Data File
The .AMI file format is a data file used by specific applications, often requiring compatible software to open across various platforms.
- .aml
AML Data File
.AML files are data files used by specific applications for structured data storage and exchange, compatible with various platforms.
- .anx
ANX Data File
.ANX files are data files used in various applications, often requiring specific software to open them.
- .apr
APR Data File
An .APR file is most commonly a Lotus Approach 97 database view/data file, registered with the MIME type application/vnd.lotus-approach. The main application associated with it is IBM Lotus Approach, part of Lotus SmartSuite.
- .art
ART Data File
.ART is an ambiguous file extension used by several unrelated formats, most notably BERNINA embroidery designs, ArtCAM/Carveco model files, and the older AOL ART image format. To open one, first identify which type of .ART file you have, then use the matching application.
- .asc
ASC Data File
.ASC files are most commonly ASCII-armored OpenPGP files: encrypted messages, public or private keys, or detached signatures. Open them with OpenPGP software such as GnuPG, Gpg4win/Kleopatra, or compatible Thunderbird features; a text editor can only show the armored text.
- .asf
ASF Data File
.ASF files are multimedia streaming container files used primarily for video and audio data, compatible with various media players.
- .asn
ASN Data File
Most .asn files users encounter in bioinformatics are ASN.1 data files, especially from NCBI tools and datasets. They are commonly opened with NCBI Genome Workbench or converted with NCBI BLAST+ tools such as blast_formatter when the file is a BLAST archive.
- .wz
WZ Data File
.WZ files are used for structured application data, imports/exports, and machine-readable workflows. Open with the originating app, text editors, or specialized data tools. This guide covers opening methods, troubleshooting, and security best practices. Common MIME type: application/x-wingz.
- .xb
XB Data File
.XB files are used for structured application data, imports/exports, and machine-readable workflows. Open with the originating app, text editors, or specialized data tools. This guide covers opening methods, troubleshooting, and security best practices. Common MIME type: model/vnd.parasolid.transmit.binary.
- .xo
XO Data File
.XO files are used for structured application data, imports/exports, and machine-readable workflows. Open with the originating app, text editors, or specialized data tools. This guide covers opening methods, troubleshooting, and security best practices. Common MIME type: application/vnd.olpc-sugar.
- .xt
XT Data File
.XT files are used for structured application data, imports/exports, and machine-readable workflows. Open with the originating app, text editors, or specialized data tools. This guide covers opening methods, troubleshooting, and security best practices. Common MIME type: model/vnd.parasolid.transmit.text.
- .aso
ASO Data File
.ASO files are most commonly specialized data files: either NCBI GenBank binary ASN.1 sequence data or Sage/Simply Accounting OFX accounting export files. Open them with the application that produced them, such as NCBI DATATOOL for GenBank data or Simply Accounting/Sage accounting software for financial exports.
- .atc
ATC Data File
.ATC is an extension used by at least two documented formats: ACUCOBOL-GT Thin Client command-line files and Autodesk AutoCAD Tool Catalog files. The correct app depends on which type of .ATC file you have.
- .atf
ATF Data File
.ATF files most commonly mean ASAM Transport Format files used with ASAM ODS test-data exchange workflows. They are text-based data and metadata files typically opened with ASAM ODS-capable engineering, measurement, or data-management software.
- .auc
AUC Data File
.AUC is officially registered for application/tamp-apex-update-confirm, a specialized Trust Anchor Management Protocol confirmation file. It is not a normal document or spreadsheet and is usually opened or processed by TAMP/PKI trust-anchor management software.
- .bak
BAK Data File
.BAK is a general-purpose backup filename extension, not one single file format. To open one, you usually need to know which program created it, such as SQL Server, AutoCAD, a text editor, a browser, or another application.
- .bar
BAR Data File
.BAR files are most commonly Qualcomm BREW Application Resource files: binary resource bundles used by BREW/Brew MP mobile applications. They usually contain compiled resources such as strings, images, and resource metadata, and are mainly opened with BREW development tools rather than everyday document viewers.
- .bdm
BDM Data File
.BDM is most commonly associated with the IANA media type application/vnd.syncml.dm+wbxml, a binary WBXML representation of an OMA Device Management message. It is usually not a normal user document and typically needs a device-management, WBXML, or binary inspection tool.
- .bed
BED Data File
.BED most commonly refers to the Browser Extensible Data format, a whitespace-delimited genomic feature file used by genome browsers and bioinformatics tools. The extension is also used by unrelated binary formats, including PLINK genotype data and a RealVNC vendor format, so the correct app depends on where the file came from.
- .bh2
BH2 Data File
.BH2 is a Fujitsu OASYS Presentation data file associated with the registered MIME type application/vnd.fujitsu.oasysprs. It is a legacy/specialized presentation format and usually requires Fujitsu OASYS Presentation or an export from the original sender.
- .bkm
BKM Data File
.BKM is most commonly a legacy BizHawk “movie” (tool-assisted speedrun input recording) file. It’s a UTF-8 text format that can be opened and played back in the BizHawk emulator, though it was replaced by .BK2 in newer BizHawk versions.
- .bmi
BMI Data File
.BMI files are most commonly associated with Autodesk 3ds Max as plug-in related files. To open or use one, you typically need Autodesk 3ds Max; on mobile systems there is usually no practical support.
- .box
BOX Data File
.BOX most commonly refers to a Preview Systems “Vbox/ZipLock” data format and is associated with the vendor MIME type application/vnd.previewsystems.box. On many systems it will not open automatically because support depends on specialized software or the workflow that created it.
- .bpd
BPD Data File
.BPD is most commonly associated with FinTS/HBCI “bank parameter data” used by German online banking software, but the same extension is also used by IBM Db2 Buffer Pool Analyzer for “buffer pool data” files.
- .bsd
BSD Data File
.BSD is most commonly associated with Beilstein Crossfire chemical data files, often identified on Linux desktops as MIME type chemical/x-crossfire.
- .bsp
BSP Data File
.BSP most commonly refers to Valve (Source/GoldSrc) compiled map files used by games and modding tools. To open one, you typically need the related game or a map/modding tool that understands BSP “lumps.”
- .c3d
C3D Data File
.C3D most commonly refers to the C3D biomechanics/motion-capture data format used to store synchronized 3D point (marker) data and analog sensor signals. It can also refer to the Chem3D chemical file format, so opening it depends on what created the file.
- .c4d
C4D Data File
.c4d files are most commonly Clonk/OpenClonk “group” data packages (C4Group) used to bundle game content such as object definitions. Open them with Clonk/OpenClonk tools or the game itself rather than trying to treat them as a single document.
- .c4f
C4F Data File
.C4F is a Clonk “group” (package/archive) file most commonly used as an Image Scenario Folder for the Clonk engine. It uses the registered media type application/vnd.clonk.c4group and is typically opened with Clonk-related tools or the game itself.
- .c4g
C4G Data File
.c4g is a Clonk/OpenClonk “group file” (a compressed game data container). You typically open it with Clonk/OpenClonk tools (especially c4group) to browse or extract its contents.
- .c4p
C4P Data File
.C4P is most commonly a Clonk player file that stores a player profile (settings, score, crew info, and sometimes a portrait) inside Clonk’s group-based data format.
- .c4u
C4U Data File
.c4u is a Clonk/OpenClonk “group file” (C4Group) used to bundle game/update data. It’s associated with the official MIME type application/vnd.clonk.c4group.
- .c9r
C9R Data File
.c9r files are Cryptomator vault objects (encrypted file contents and metadata) and are meant to be opened by unlocking the vault with Cryptomator, not by a regular document viewer.
- .c9s
C9S Data File
.c9s files are Cryptomator encrypted files stored inside a Cryptomator vault. You typically open them by unlocking/mounting the vault with Cryptomator rather than opening the .c9s file directly.
- .cac
CAC Data File
.CAC is most commonly a CAChe MolStruct chemical structure file used in chemistry software and converters. On desktops, it can be handled via chemistry toolchains such as Open Babel (format support is write-only there).
- .cap
CAP Data File
.CAP is most commonly a network packet capture file (pcap) containing captured network traffic. You typically open it with Wireshark or other pcap-compatible tools rather than renaming the file.
- .car
CAR Data File
.car is a Content Addressable aRchive (CAR) used in the IPFS/IPLD ecosystem to bundle content-addressed blocks for transport and exchange. You typically open or create it with IPFS tooling (Kubo) or CAR utilities/libraries rather than a desktop “viewer”.
- .cat
CAT Data File
.CAT files are most commonly Windows security catalog files used to store hashes and digital signatures for validating drivers and system components. They are typically inspected or verified with Windows security tools rather than “opened” like documents.
- .cda
CDA Data File
.CDA files are not real audio files; they are small Windows-generated track shortcut entries for songs on an audio CD (CD-DA/“Red Book”). They only work when the referenced audio CD is available in a disc drive.
- .cdf
CDF Data File
.cdf most commonly refers to NASA’s Common Data Format (CDF), a self-describing scientific data container for scalar and multidimensional datasets. You typically open it with scientific tools such as MATLAB, Python libraries (SpacePy/CDFlib), Wolfram Language, or NASA’s CDF utilities.
- .cdx
CDX Data File
.CDX is the ChemDraw Exchange (CDX) binary file format used to store chemical structures and drawings. It’s most commonly opened with ChemDraw-compatible chemistry tools or converted via CDXML or other chemical formats.
- .cdy
CDY Data File
.CDY files are Cinderella construction files used by the Cinderella interactive geometry software. Open them with Cinderella, or use a compatible geometry viewer such as OK Geometry for browsing.
- .cea
CEA Data File
.CEA most commonly refers to CEA-2018 task-model XML (a standard “CEA” format) or to data/input used with NASA’s Chemical Equilibrium with Applications (CEA) workflow. How you open it depends on which of these your file actually is.
- .cef
CEF Data File
.CEF can refer to two different things: a chemical structure exchange file (often treated like CXF) or a Common Event Format (CEF) text log used in security tools. How you open it depends on which CEF you have.
- .chm
CHM Data File
.CHM is Microsoft Compiled HTML Help: a single-file help manual that packages HTML pages, navigation, and search into one binary container. It is most commonly opened on Windows, with viewer options on Linux and limited options on mobile.
- .cif
CIF Data File
.cif is a Crystallographic Information File used to store and exchange crystallography data (structures, metadata, and related measurements). It’s typically opened with crystallography tools (for example, Mercury) or chemistry toolkits (for example, Open Babel).
- .cii
CII Data File
.cii is most commonly associated with the registered MIME type application/vnd.anser-web-certificate-issue-initiation. In practice, it is typically handled by the specific ANSER-WEB/terminal client workflow that created it rather than by general-purpose apps.
- .cil
CIL Data File
.CIL is most commonly a Microsoft Clip Gallery packaged file used to distribute clip art collections. It’s typically opened with Microsoft Clip Gallery / Microsoft Office-era tools, and may be difficult to use on modern non-Windows systems.
- .bnk
Bank File Format
.bnk files are versatile, used in gaming for audio data and in finance for data storage, requiring specific software to open.
- .cla
CLA Data File
.CLA is most commonly associated with the IANA-registered MIME type application/vnd.claymore and is used by Claymore-related software. On most systems, you open it by using the originating Claymore application rather than a built-in viewer.
- .cld
CLD Data File
.CLD can refer to two unrelated formats: (1) an OpenVMS command definition file used by DIGITAL Command Language (DCL), or (2) an Illuscio volumetric imaging CLD point data/metadata file (IANA media type model/vnd.cld). How you open it depends on which one you have.
- .cmc
CMC Data File
.CMC most commonly refers to a CosmoCaller data file and is associated with the registered MIME type application/vnd.cosmocaller. It is typically ASCII text, so it may be viewable in a text editor when you don’t have the creating app.
- .cml
CML Data File
.cml is most commonly a Chemical Markup Language (CML) file: an XML-based format for storing and exchanging chemical information such as molecules, reactions, and associated data.
- .cmp
CMP Data File
.CMP is an ambiguous extension used by multiple applications, so the correct way to open it depends on what created the file. In web/content contexts, .cmp is commonly mapped to the registered MIME type application/vnd.yellowriver-custom-menu.
- .cod
COD Data File
.COD files are most commonly BlackBerry application binaries used for installing apps on BlackBerry devices (often delivered “over the air”). They are not general-purpose “data files” and typically won’t open meaningfully in standard desktop apps.
- .cpa
CPA Data File
.CPA is most commonly associated with the “Compass Takahashi” chemical file type and is mapped by shared-mime-info to the non-standard MIME type chemical/x-compass. Because .CPA is ambiguous, some .CPA files may belong to unrelated software, so identifying the file’s origin is key to opening it correctly.
- .cpl
CPL Data File
.CPL is most commonly an XML-based Call Processing Language (CPL) script used to control Internet telephony call handling; on Windows, .cpl is also widely known as a different thing: Control Panel applet executables.
- .csf
CSF Data File
.CSF is most commonly a CAChe MolStruct chemical structure data file. It’s typically handled by cheminformatics tools such as Open Babel for conversion/export rather than general-purpose apps.
- .csl
CSL Data File
.csl files are Citation Style Language (CSL) style definitions used to format citations and bibliographies. They are XML-based and are commonly installed/used by citation managers such as Zotero.
- .csm
CSM Data File
.CSM most commonly refers to a plain-text script/configuration file used by OpenCSM/Engineering Sketch Pad (ESP) for constructive solid modeling. The same .CSM extension is also used for optical motion-tracking marker data in Character Studio workflows, so the right app depends on where the file came from.
- .csp
CSP Data File
.CSP most commonly refers to a CommonSpace data file (MIME: application/vnd.commonspace), a binary format created by CommonSpace software. Because “.csp” is also used for unrelated web/server page formats, identifying the originating app is key to opening it correctly.
- .cst
CST Data File
.CST is most commonly a CommonSpace document file. You typically open it with software that supports CommonSpace documents; otherwise, use the correct app association on your system.
- .ctx
CTX Data File
.CTX is an ambiguous extension most commonly seen as either a chemical structure data file (Gasteiger group CTX) or a Visual Basic UserControl binary data file used with VB projects.
- .cub
CUB Data File
.cub is most commonly a Gaussian Cube file: a plain-text scientific data format that stores volumetric values (for example electron density or molecular orbitals) on a 3D grid plus atom coordinates.
- .cuc
CUC Data File
.CUC is most commonly a Trust Anchor Management Protocol (TAMP) “Community Update Confirm” message file, identified by the media type application/tamp-community-update-confirm. The same .cuc extension is also used by Naviter SeeYou for “Contest file (CUC)”, so the correct app depends on where the file came from.
- .cwl
CWL Data File
.cwl files are Common Workflow Language (CWL) documents that describe command-line tools and workflows. You typically open and run them with a CWL runner such as cwltool or another CWL implementation.
- .cww
CWW Data File
.CWW is an ambiguous extension most commonly seen as either a Crossword Weaver puzzle file or a WoodWorks (structural engineering) binary database file. To open it, first identify which program created it, then use the matching desktop application.
- .cxf
CXF Data File
.CXF is most commonly a Chemical eXchange Format (CXF) file used to exchange chemical structure and related data between cheminformatics tools. It is typically opened with chemistry software such as CAS STN Express.
- .dae
DAE Data File
.DAE is most commonly a COLLADA Digital Asset Exchange file: an XML-based 3D scene/model format. You typically open it by importing it into a 3D application (or a GIS/3D city tool) that supports COLLADA.
- .daf
DAF Data File
.DAF is most commonly a Rocket Mobius Document Archive File used in Mobius content management/archive workflows. To open it, you typically need Rocket Mobius software (for example Mobius View) or access to the Mobius system that created it.
- .dbf
DBF Data File
.DBF is a dBASE table file used to store rows and columns of data. It’s widely supported by database/spreadsheet tools and is also commonly used as the attribute table in ESRI Shapefiles.
- .dcd
DCD Data File
.DCD most commonly refers to a molecular dynamics trajectory file used by tools like VMD and libraries like MDAnalysis, or to an ASAM GDI “DCD” document used in automation/test bed systems (IANA: application/DCD). To open it successfully you usually need companion files (e.g., a structure/topology) and software that matches the specific DCD meaning.
- .dcm
DCM Data File
.DCM most commonly refers to a DICOM medical imaging file (DICOM Part 10), used to store images and related clinical metadata.
- .dcr
DCR Data File
.DCR files are data files often associated with Adobe Director, used for multimedia content. They can be opened using specific software on various platforms.
- .dd2
DD2 Data File
.dd2 is most commonly an Open Mobile Alliance (OMA) Download Descriptor 2 file: an XML “descriptor” used by mobile download-over-the-air (DLOTA) workflows. It is typically opened as XML (in a text/XML viewer) or handled by software implementing the OMA DLOTA specification.
- .ddd
DDD Data File
.DDD is a registered Fuji Xerox 2D CAD data format. It is most reliably opened with the Fuji Xerox-associated applications listed in the IANA registration (EDMICS 2000 and DocuFile).
- .ddf
DDF Data File
.DDF is an ambiguous extension most commonly seen as an XML “Device Description Framework” file used with SyncML/OMA device management and Windows MDM, but it is also used by other tools (notably IBM Sterling B2B Integrator and IAR Embedded Workbench). Opening it depends on which product created it.
- .dii
DII Data File
.DII is most commonly a Summation image/batch load file used in litigation support to import document records and link them to image files. It is typically opened or imported by eDiscovery/litigation support tools rather than viewed like a normal document.
- .dim
DIM Data File
.DIM most commonly refers to a Fast Copy disk image file used by disk imaging/recovery tools. It is typically opened by the vendor utilities that created it, and sometimes by disk-image tooling depending on how the image was produced.
- .dir
DIR Data File
.DIR is most commonly an Adobe/Macromedia Director authoring (project/source) file used with Director and the Shockwave/Director ecosystem. It is considered obsolete and typically requires an older Director installation to open properly.
- .dis
DIS Data File
.DIS files are most commonly Oracle Discoverer Desktop workbooks. They are typically opened with Oracle Discoverer Desktop and may also be identified by the IANA-registered MIME type application/vnd.Mobius.DIS.
- .dit
DIT Data File
.DIT is an ambiguous extension most commonly associated with Microsoft Active Directory’s database file (Ntds.dit) and, in a different context, IBM Planning Analytics dimension interface files (.dit). Opening it depends on which application produced it, and many .DIT files are not meant to be opened directly by end users.
- .dmp
DMP Data File
.DMP files are most commonly crash dump (core dump) files that capture a snapshot of memory for debugging after a crash. On Windows, they’re typically opened and analyzed with WinDbg or Visual Studio.
- .dna
DNA Data File
.dna most commonly refers to a SnapGene native DNA file used in molecular biology to store sequences and annotations in a binary format. It is typically opened with SnapGene or tools that can parse or convert SnapGene .dna files.
- .dor
DOR Data File
.DOR files are typically Archicad Door library part data related to Graphisoft’s GDL (Geometric Description Language). They are opened most reliably in Graphisoft Archicad, which supports GDL-based library part workflows.
- .apc
Atari Portfolio Compressed File
APC files are compressed data files used by the Atari Portfolio, a palmtop computer from the late 1980s.
- .dpg
DPG Data File
.DPG files are data files used by specific applications and can be opened with compatible software across various platforms.
- .dsm
DSM Data File
.DSM is most commonly a DeSmuME “movie” (input recording) file used for Nintendo DS emulation replays and tool-assisted speedruns. You typically open it in the DeSmuME emulator rather than in a media player.
- .dtd
DTD Data File
.dtd files are Document Type Definition files used with XML (and related SGML-family) documents to define the allowed structure, elements, and entities. You typically open them in a text editor or an XML-aware editor/IDE.
- .dvc
DVC Data File
.DVC most commonly refers to Data Version Control (DVC) metadata files used to track datasets/models in data/ML projects. The same extension can also refer to IDRISI Vector (DVC) GIS data files, so how you open it depends on where the file came from.
- .gsd
General Station Description
GSD files are used to describe the configuration of field devices in industrial networks.
- .kc2
Kaspersky Anti-Virus Data File
KC2 files are data files used by Kaspersky Anti-Virus software to store various configuration and update data.
- .m2s
Motion Simulation File
.m2s files are used for storing motion simulation data, typically in engineering or animation software.
- .ml20
Machine Learning Model Format 2020
.ml20 files are used for storing machine learning models, typically created by specific machine learning frameworks.
- .rva
RVA File Format
RVA files are used for storing specific data configurations in specialized software applications.
- .thd
Thread File
THD files are typically used to store thread data for embroidery machines or software.