Data file extensions
Structured machine-readable files used by apps, APIs, and automation workflows.
Total extensions in this category: 146
Extensions in Data
Explore the most searched extensions in this category.
- .json
JSON data
.json files store structured data as plain text using the JSON (JavaScript Object Notation) format. They’re commonly used for web APIs, app configuration, and data exchange, and can be opened with any text editor or JSON-aware tools.
- .db
SQLite 3 Database
.db is commonly used for SQLite 3 database files—single-file relational databases used by many apps. You can open them with SQLite tools and many database browsers.
- .yaml
YAML File
.yaml is a YAML document: a human-readable data serialization format commonly used for configuration files and data exchange. You can open it with a text editor, or with editor support such as the YAML extension for Visual Studio Code.
- .sqlite3
SQLite 3 database
.sqlite3 is a SQLite version 3 database stored as a single cross-platform file. You can open it with SQLite’s sqlite3 command-line shell or any SQLite-capable database browser/library.
- .sqlite
SQLite 3 Database File
.sqlite is a SQLite 3 database stored as a single file. You open it with SQLite tools (for example, the SQLite command-line shell) or any application that supports SQLite.
- .jsonl
JSON Lines (newline-delimited JSON)
.jsonl is a JSON Lines file: plain text where each line is a complete JSON value, commonly used for logs and large datasets that are processed record-by-record.
- .parquet
Apache Parquet columnar data file
.parquet is an open, column-oriented file format for efficient storage and retrieval of tabular data. It’s commonly opened with data tools such as pandas (Python) and other analytics/ETL software that supports Apache Parquet.
- .ndjson
Newline-Delimited JSON (NDJSON)
NDJSON is a text format where each line is a complete JSON object, making it convenient for streaming and log-like datasets. You can open it with any text editor, and many data tools can process it line-by-line.
- .pkpass
Apple Wallet Pass
.pkpass files are Apple Wallet passes used for things like tickets, boarding passes, coupons, and loyalty cards. They’re designed to be added to Apple Wallet and may also work with some third‑party wallet apps on Android.
- .feather
Apache Arrow Feather (Arrow IPC file) format
.feather is a binary, columnar data file used to store and exchange data frames efficiently using Apache Arrow. It is commonly opened from Python (pandas/pyarrow) or R (arrow).
- .dat
Application-specific .DAT file
.dat files are generic data files that can contain various types of data, often used by specific applications.
- .arrow
Apache Arrow IPC File (Feather V2)
.arrow files store data in Apache Arrow’s IPC file format for fast, cross-language columnar analytics. They are commonly read and written by Arrow libraries such as PyArrow (Python) and the Arrow R package.
- .avro
Apache Avro Object Container File
.avro files store Apache Avro serialized data, usually inside an Avro “object container” that includes the schema and data blocks. They’re commonly opened by big-data tools and SQL engines such as Apache Spark, Apache Hive, and DuckDB.
- .cl
CL data
.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
.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
CU-Writer document (.cw)
.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
.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
.dp files are most commonly OSGi Deployment Packages: standard JAR (ZIP) archives used to deploy/update software on OSGi-based systems.
- .dx
DX data
.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
.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
.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
FrameMaker-related document (.fb)
.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
Adobe FrameMaker document (.fm)
.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
.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.
- .h5
HDF5 hierarchical data (.h5)
.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.
- .le
LE data
.le files are most commonly Bluetooth Low Energy (BLE) Out-of-Band (OOB) data files, associated with the IANA-registered media type application/vnd.bluetooth.le.oob. They typically contain BLE advertising/scan response-style data used for secure pairing (often via NFC).
- .ma
MA data
.MA most commonly refers to a Wolfram/Mathematica notebook or Wolfram Language source file. Open it with Wolfram software (e.g., Mathematica/Wolfram Desktop) rather than renaming the extension.
- .me
ME data
.ME most commonly refers to a troff/groff “ME” macro package input document (a text file used for typesetting). You can open it in a text editor, or render it to PDF/PostScript using groff.
- .mm
MM data
.mm is most commonly a FreeMind/Freeplane mind map file saved as plain XML. You can open it with mind-mapping apps such as FreeMind or Freeplane, or view it as text in an XML-capable editor.
- .ms
MS data
.ms most commonly refers to a troff/groff “ms” macro document (a plain-text manuscript source file). You open it with roff tools like groff (to render to PDF/PS/HTML) or a text editor (to view/edit the source).
- .nb
NB data
.NB is the native Wolfram Notebook file format used by Wolfram Language products (e.g., Mathematica, Wolfram Desktop, Wolfram Player). Open it with a Wolfram notebook application rather than renaming the extension.
- .nq
NQ data
.nq is most commonly an N-Quads file: a plain-text, line-based RDF dataset format standardized by W3C. You open it with RDF tools and libraries (for example Apache Jena, Eclipse RDF4J) or software that can import N-Quads.
- .nt
NT data
.nt files are typically N-Triples: a plain-text, line-based RDF (Resource Description Framework) serialization standardized by the W3C. You can open them in RDF tools (e.g., Apache Jena, Eclipse RDF4J) or view them with any text editor.
- .cue
Cue Sheet File
CUE files are metadata files that describe the layout of tracks on a CD or DVD.
- .ob
OB data
.OB is an ambiguous extension used by multiple applications for proprietary data. To open it, you need to identify which program created the file and use that program (or its modding tools) rather than relying on a universal viewer.
- .p8
P8 data
.p8 most commonly contains a PKCS #8 private key (often PEM-encoded text) used for cryptographic authentication and signing, including Apple Push Notification service (APNs) token-based auth keys. You typically open it with key-management tools (like OpenSSL) or import it into the app/service that requested the key.
- .pt
PT data
.PT most commonly refers to a “page table” data file associated with the vendor MIME type application/vnd.snesdev-page-table. It’s a niche data format, so you typically need a toolchain that understands that specific MIME/format rather than a general-purpose viewer.
- .rdc
RenderDoc Capture File
RDC files are used to store graphics rendering data captured by RenderDoc, a graphics debugger.
- .rd
RD data
.rd usually refers to an MDL RDfile (reaction-data file) used in cheminformatics to store chemical reactions plus associated data fields. The same extension is also used for R documentation files (.Rd), so identifying the file’s origin is important before choosing software.
- .rl
RL data
.RL is most commonly an XML “Resource Lists” document (RFC 4826) associated with the MIME type application/resource-lists+xml. Some .RL files may also be application-specific data files (e.g., FileInfo notes .RL files created by R.viewer that store lists of files/folders).
- .rq
RQ data
.rq is most commonly a SPARQL query file used to store and run SPARQL queries against RDF datasets. You typically open it in a text editor to view/edit, or run it with SPARQL tools such as Apache Jena ARQ.
- .sc
SC data
.SC is most commonly a SuperCollider source/code file used for audio synthesis programming. In enterprise contexts, the .sc extension is also mapped to the registered MIME type application/vnd.ibm.secure-container, so you may encounter .sc files that are secure-container data rather than code.
- .duckdb
DuckDB database file
.duckdb is DuckDB’s on-disk, single-file database format used to store tables and other database objects in one file.
- .sd
MDL SDfile (chemical structure / SDF)
.sd most commonly refers to an MDL “SDfile” (Structure-Data File / SDF): a text-based chemical structure format that stores molecular connection tables plus associated properties. It is widely supported by cheminformatics tools such as Open Babel.
- .sm
SM data
.SM is most commonly a StepMania “simfile” (stepchart) that describes a rhythm-game song’s metadata and note charts. You open it with StepMania-compatible games or stepchart editors such as ArrowVortex.
- .sr
SR data
.sr is a sigrok “session” capture file used to store logic analyzer/oscilloscope acquisition data and metadata. It is the native format for sigrok tools such as PulseView and can be opened on desktop platforms with sigrok frontends.
- .st
ST data
.ST is an ambiguous file extension used by multiple, unrelated formats. To open it, you usually need to know which program created the file (common uses include tracker/music-related files and a SailingTracker track MIME mapping).
- .ac2
AC2 data
.AC2 files are data files used by Banana Accounting for managing financial information, including transactions and budgets.
- .acc
ACC data
.ACC files are specialized data files used by specific applications, often related to security systems, and require compatible software to open.
- .acu
ACU data
.ACU files are compiled data files used by COBOL applications to execute code efficiently across platforms.
- .aep
AEP data
.AEP files are project files used by Adobe After Effects for creating motion graphics and visual effects.
- .afp
AFP data
.AFP files are specialized data files used primarily in high-volume printing and document management systems, supporting complex document layouts.
- .age
AGE data
.AGE files are specialized data files used in specific applications, requiring compatible software to open.
- .ait
AIT data
.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
.ALC files are specialized data files used by certain applications, often related to chemical data processing.
- .sw
SW data
.sw is an ambiguous extension most often seen either as UniProt/Swiss-Prot protein “flat file” data or as a raw signed 16-bit PCM audio file. To open it, first identify which kind you have (bioinformatics text vs. raw audio) and then use the appropriate tool.
- .uo
UO data
.UO files are most commonly UOML (Universal Office Markup Language) documents—an XML-based format. You can open them with an XML-capable editor or viewer; some systems may identify them by the MIME type application/vnd.uoml+xml.
- .wg
WG data
.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
.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
.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
.A2L files are data files used in automotive systems for calibration and measurement of ECUs.
- .ami
AMI data
The .AMI file format is a data file used by specific applications, often requiring compatible software to open across various platforms.
- .aml
AML data
.AML files are data files used by specific applications for structured data storage and exchange, compatible with various platforms.
- .anx
ANX data
.ANX files are data files used in various applications, often requiring specific software to open them.
- .apr
APR data
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
.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
.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.
- .asn
ASN data
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
.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
.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
.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
.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
.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
.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
.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
.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
.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
.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
.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
.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
.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
.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
.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
.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
.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
.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
.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.”
- .c9r
C9R data
.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
.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
.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
.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
.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
.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.
- .cdf
CDF data
.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
.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
.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
.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
.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
Microsoft Compiled HTML Help (.CHM)
.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
.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
.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
.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
.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
.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
.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
Chemical Markup Language (.CML)
.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
.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
.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
.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
.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
.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
.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
.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
.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
.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
.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
.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
.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
.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
.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
.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.
- .daf
DAF data
.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.
- .dcd
DCD data
.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
.DCM most commonly refers to a DICOM medical imaging file (DICOM Part 10), used to store images and related clinical metadata.
- .dcr
DCR data
.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
.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
.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
.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
.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
.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
.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
.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
.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
.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
.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
.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
.DPG files are data files used by specific applications and can be opened with compatible software across various platforms.
- .dsm
DSM data
.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.
- .dvc
DVC data
.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.
- .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.