CAR File

What are CAR files and how to open them

Are you having problems opening a CAR file or are you simply curious about its contents? We're here to explain the properties of these files and provide you with software that can open or handle your CAR files.

What is a CAR file?

CAR files have multiple uses, and Atari Cartridge Dump is one of them. Read more about the other uses further down the page.

Atari Cartridge Dump File

Atari Cartridge Dump File stores a complete image of a ROM cartridge for the Atari 8-bit home computers (models 400/800, XL, XE, etc.). It is created by emulator software (for example the Atari800 emulator) or cartridge-dumping tools. It bundles the cartridge's machine type, size, and integrity information alongside the raw ROM data so that emulators can load the cartridge correctly every time, without requiring the user to manually select its type or bank-switching scheme.

The header section is sixteen bytes long and precedes the actual ROM contents. The first four bytes are the ASCII characters CART, which identify this type of cartridge image. The next four bytes encode the cartridge type in big-endian numeric form; following that are four bytes containing the checksum of the ROM (for read-only cartridges). The fourth four-byte block is reserved (currently zero), not used for data but maintained for compatibility. After the header comes the ROM data itself, whose size depends on the cartridge - common sizes include 4-, 8-, 16-, 32-, 40-, 64-, 128-, 256-, 512-, or 1024-kilobyte images.

Byte signature: the first bytes are 43 41 52 54 (ASCII "CART"), followed by zeros in the reserved area at offset zero.

How to open CAR files

Important: Different programs may use files with the CAR file extension for different purposes, so unless you are sure which format your CAR file is, you may need to try a few different programs.

While we have not verified the apps ourselves yet, our users have suggested ten different CAR openers which you will find listed below.

Last updated: August 25, 2026

All known file formats using extension .CAR

While Atari Cartridge Dump File is a popular type of CAR-file, we know of 17 different uses of the .CAR file extension. Different software may use files with the same extension for different types of data.

Biosym Archive File

Biosym Archive Files hold the three-dimensional coordinates of all atoms in a molecular model, as created by Biosym/MSI's Insight II / Discover / BIOVIA Materials Studio for chemistry and molecular modelling. These files capture the spatial positions of atoms (x, y, z coordinates), residue names, element symbols, optional partial charges, and may include unit-cell information under periodic boundary conditions. They are used alongside a matching Molecular Definition File (.mdf) that holds topology, atom types, and connectivity.

The format is plain-text ASCII, human readable. The first line is a header like "!BIOSYM archive 3" (or "archive 1" in older versions), followed by a flag PBC=ON or PBC=OFF indicating whether periodic boundary conditions are used. If PBC=ON, a unit‐cell record giving cell lengths a, b, c and angles α, β, γ follows. The rest of the file lists atoms one record per line with fields for atom name, Cartesian coordinates in angstroms, residue or molecule identifier, element symbol, partial charge, and optional sequence number.

Users of Materials Studio, Open Babel, Avogadro, VMD and related tools load this file together with its .mdf partner to reconstruct molecular structure and chemical context. The .car file does not by itself define bond connectivity or atom types - those come from the .mdf or force-field (.frc) files.

Technical identifiers: the file begins at offset 0 with ASCII signature "!BIOSYM archive …" (e.g. version 3), contains the strings "DATE" and "FILE" in the header lines, and uses fixed-column or space‐separated fields for atom records.

Brew Component Application Resource File

CAR stands for Component Application Resource. The CAR files contain information about the assets that are available for a software application being run on the Brew Mobile Platform. This platform is used to operate applications on a variety of mobile phones.

The CAR files are compiled into a binary BAR file. This file is automatically loaded when the application is run.

CAR opener for Windows

We have identified one CAR opener that is compatible with this specific type of CAR file.

C64 Archiver Archive

C64 Archiver Archive holds a set of files and directories from a Commodore 64 system, along with metadata about each item, all packed into one single archive for transfer or backup. Files created by the C64 OS application C64 Archiver are stored this way so that filenames, file types, directory structure, and other native C64 filesystem attributes are preserved intact. It works like a TAR archive on Unix but is tailored for Commodore-64 environments.

The archive writer records a root item (either a file or a directory) and then serialises the entire directory tree beneath it. Supported file types include PRG and SEQ, plus directories; CBM filesystem metadata such as file size in bytes, lock status, and PETSCII filenames are stored. There are three archive-types: General for full flexibility; Restore for creating full system snapshots; and Install for overlay updates to existing systems.

CAR format has versioned headers. Version 2 introduced a short note field of up to 30 characters; version 3 adds an optional CRC32 checksum for verifying integrity. The header includes an archive type code, version number, timestamp of creation, and in version ≥2 the note. Each item in the directory tree is preceded by its own header storing either filename and file metadata or directory name and child count.

Signature for identification: each file begins with the magic string ".64.RCHIVE" (bytes C3 36 34 C1 52 43 48 49 56 45 at offset 1); all CAR files contain the ASCII string "RCHIVE" somewhere in the file.

CAR Compressed Archive File

A CAR compressed archive is a file format used by SAP's CAR and SAPCAR utilities to package and compress software components, support packs, or updates for SAP systems. The utility writes archives carrying multiple files and metadata in a single container, often used to deliver installation packages.

Files in the archive are stored with metadata including file permissions, timestamp, file size, and checksum. When unpacking, SAPCAR reads these metadata and extracts each component into the file system while preserving intended attributes. The CAR utility was used in older SAP releases (up to version 4.6B), after which SAPCAR became the main tool; SAPCAR still supports reading CAR files.

The container begins with a text-based archive header including a magic string of four bytes "CAR " or "CAR\0" (that is, ASCII letters C A R followed by space or NUL), followed by a version number such as "2.00" or "2.01".

Carnivores Graphics And Behavior File

Carnivores Graphics And Behavior File holds 3D models for living and interactive entities in the Carnivores video games (Carnivores, Carnivores 2, Carnivores Ice Age), including animals, the hunter, weapons, dropship, and wind indicator. The game uses these files to store both the appearance (geometry, textures, faces, vertices) and behavior-linked data like animations and sounds.

Each file is produced during development of the game, typically by the original model and animation tools. Once created, the game engine loads the file during play; it does not embed the model in external objects. Both static and animated components are included, where static meshes describe shape and texture mapping, while animation tracks (vertex-animation) and sound clips define how that model behaves.

Inside such a file, the beginning-portion (header) defines model‐level metadata including texture name, numbers of animations, sounds, vertices, and faces; that is followed by lists of face definitions (vertex indices, texture coordinate indices, face flags), vertex definitions (3D positions, vertex ownership, hidden-flag), the embedded texture data (always a 256-pixel width image with 16-bit BGRA5551 style color), animation data (name, keyframes per second, frame count, per-frame per-vertex offsets), sound records (name and PCM data), and a cross-reference table mapping animations to sounds. The header contains an ASCII chunk "msc: #" near byte offset 8 or 24 depending on the version.

Carrara Environment File

This file stores environment data for Carrara, a 3D graphics application made by DAZ 3D used for modeling, lighting, skies, terrains, and rendering. It captures settings that define how the "world" looks around models - such as sky, atmospheric effects, distant lights, ground plane, fog, clouds or background maps - so when you render or preview, you see those surroundings appropriately.

The Carrara program creates and uses this format. Users design or adjust environmental parameters - it could be an outdoor sky setup, or backdrop scene - and save them as .CAR files. These files can be loaded later to apply the same environment to other scenes or reused as part of scene presets. The file may embed or reference textures, shaders, lighting rigs, and camera orientation relevant to the environment.

Technically, the file begins with the ASCII signature 3DC{ at byte offset 0. Internally it includes keywords like UNIVERSE and DEFAULT as part of its data structure.

Programs that open these CAR files

We have identified one CAR opener that is compatible with this specific type of CAR file.

CCS64 Cartridge Dump File

The CCS64 Cartridge Dump File format stores the complete image of a Commodore/CBM computer cartridge. It was defined by Per Håkan Sundell for the CCS64 emulator with input from others (also used in VICE). The format preserves hardware‐type, memory mapping, control-line status (EXROM and GAME), cartridge name, data banks or "chip" contents, and how the cartridge should appear to the emulated system. It is used by the emulator to load cartridge images directly, including special utility, freezer or bank-switched cartridges.

Files are created by emulator tools or cartridges dumping utilities that produce CCS64-/VICE-compatible images. When emulated, the cartridge image's header tells the emulator the cartridge hardware type, which determines how the cartridge will start up (for example, where in Commodore memory its ROM or RAM will be mapped and whether EXROM/GAME lines are active). Then the file includes one or more "CHIP" packets that each describe a contiguous block of ROM or RAM including which bank it belongs to, where it loads in the Commodore address space, and the length of that block.

Files begin with a 16-byte ASCII signature: "C64 CARTRIDGE " padded with spaces; this helps distinguish this format among others. The file header includes fields such as a 4-byte length from the start (default 0x40), a version number, a hardware type code, one byte each indicating the status of the EXROM and GAME lines, a 32-byte name (null-terminated), then from offset 0x40 onward a series of CHIP packets. Each CHIP packet starts with "CHIP", a packet length, chip type (ROM, RAM etc.), bank number, load address, block length, and then the data bytes.

Cellsprings CA Rule File

We know that one CAR format is Cellsprings CA Rule File. We have not yet analyzed in detail what these files contain and what they are used for. We're working on it.

Compressia Archive File

Compressia Archive is a file format used by the Compressia archiving program developed by Yaakov Gringeler. It bundles together multiple files into a single compressed archive that can be both created and extracted using Compressia. When Compressia is installed, it writes native archive files in this format to archive collections of files on MS-DOS or Windows platforms, principally under its 1.0 beta releases from 2003.

During its trial period (30 days), Compressia allows both creation and extraction of these archives. After the trial ends, archive creation is disabled, but extraction remains possible so that existing archives can still be opened and their contents retrieved.

Files of this type begin with a specific signature: the first bytes (offset 0) are the ASCII string "CMP0CMP1". This serves to uniquely identify the archive format from other uses of the same file extension.

Content Addressable Archive

Content Addressable Archive files are data bundles created by systems that use content-addressing to store blocks of data alongside identifiers that uniquely refer to them. Such files package together a header listing the archive's root identifiers followed by a sequence of blocks. Each block begins with an identifier field and then the data content, allowing independent verification or retrieval of each part. These archives help transfer or backup content-addressed data structures such as directed acyclic graphs.

A CAR file is produced by software working with IPLD (InterPlanetary Linked Data) data, notably in the IPFS, Filecoin, and AT Protocol ecosystems. The header encodes a fixed version number (currently 1) and one or more "root" identifiers known as CIDs, which anchor one or more DAGs (Directed Acyclic Graphs) inside the file. After the header, any number of blocks follow; each block includes a CID followed by the data that the CID points to. This layout makes it possible to extract or verify pieces independently.

Internally, the file begins with a header section preceded by a varint length prefix, encoding a DAG-CBOR object containing at least the keys "version" and "roots" (version is always integer 1). Blocks are encoded similarly: a length prefix, then the CID (exactly 36 bytes in many implementations), then the content data. Some files include internal identifiers, such as a string "GVERSION" or "EROOTS", and in some cases a byte-signature starting near byte offset 1 matching the ASCII string ".eroots".

NASCAR Racing Car Data File

We know that one CAR format is NASCAR Racing Car Data File. We have not yet analyzed in detail what these files contain and what they are used for. We're working on it.

NeoBook Cartoon File

NeoBook Cartoon File stores animated cartoon sequences for use within NeoBook, a Windows multimedia authoring environment developed by NeoSoft Corp. These files hold frames of artwork and timing/looping data to play back short animations (cartoons) inside NeoBook publications.

NeoBook writes Cartoon Files when animations are created using its built-in drawing or frame-sequence tools. These animation files are played using NeoBook's PlayCartoonFile action in VisualNEO or similar NeoBook publishing tools, specifying where on a page the cartoon appears, its speed, repetition, and other display properties.

Files begin with the signature bytes 53 4E 0C 00 at the very start. At offset 11 they contain the ASCII string ".PNG........IHDR", indicating inclusion of PNG image data (specifically the IHDR chunk) embedded in the file.

VICE C128 Cartridge

VICE C128 Cartridge files store ROM cartridge images for the Commodore 128 emulator module of VICE (Versatile Commodore Emulator). They are used to emulate hardware cartridges designed specifically for the C128, including both generic function ROM cartridges and those with special behavior like bank-switching or added RAM. These files enable loading cartridge ROMs when booting the emulator in C128 mode so that the emulated machine behaves as if the cartridge were physically plugged into its expansion port.

These files are produced and consumed by the VICE emulator. They are created when dumping or packaging cartridge ROMs into the CRT file format (VICE's cartridge file format), and read by VICE when attaching cartridges to a virtual C128. Some cartridges work only in C128 mode and are flagged as C128 cartridges. There is support for generic 8 KiB or 16 KiB ROM blocks (named ROML and ROMH) mapped to the standard addresses ($8000-$BFFF and $C000-$FFFF), with smaller ROMs mirrored if necessary. Specialized cartridges have dedicated identifiers (CRT IDs) such as Warpspeed128, Partner 128, Comal 80, Magic Desk 128, Gmod2-C128.

The file begins with a 16-byte signature, padded with spaces, identifying it as a C128 cartridge image: "C128 CARTRIDGE ".

VICE CBMII Cartridge

The VICE CBMII Cartridge format stores ROM data for a cartridge that plugs into a Commodore CBM-II computer, allowing emulated CBM-II machines (model lines 5x0 or 6x0/7x0) to load extra machine code, BASIC extensions, utility functions or specialized add-ons. It is used by the VICE emulator family. These cartridge image files provide a way to emulate physical game or utility cartridges for the CBM-II line.

Files are created by dumping the ROM contents of a CBM-II cartridge or utility module, formatting them according to the CRT (Cartridge) file standard as implemented in VICE version 2.0 and later. Once in this format, the emulator reads them and maps their ROM into the correct memory regions (such as $1000-$1FFF, $2000-$3FFF, $4000-$5FFF or $6000-$7FFF, depending on the cartridge design). The emulator also uses metadata in the cartridge header to know which bank switching or control-line signals to emulate in order to mimic the behavior of the real hardware.

The file begins with a 16-byte signature identifying it as a CBM-II cartridge: the ASCII header "CBM2 CARTRIDGE " (padded with spaces) at offset 0. This signature is part of the general CRT header structure used by VICE for multiple Commodore models, and distinguishes these files from cartridges for C64, VIC-20, PLUS4 etc.

VICE PLUS4 Cartridge

The VICE PLUS4 Cartridge format is a file used for emulating cartridge hardware on the Commodore PLUS/4 computer. It is produced by the VICE emulator, a program that mimics the behavior of the original PLUS/4 machine in software. The purpose of this format is to store cartridge ROM images - including multi-bank cartridges - that emulators can load to replicate how physical cartridges would function on the actual hardware.

Cartridge images in this format usually contain fixed-size ROM data divided into banks of either 16 KiB or 32 KiB, depending on the cartridge type. They include information about how many banks are present and how the emulator should switch between them, as well as what memory addresses they occupy. This allows games or additional functionality stored in cartridge form to integrate seamlessly with the PLUS/4's memory map during emulation. The VICE emulator reads these files to map in the cartridge ROM(s) and handle bank switching so that software designed for cartridge use runs correctly.

Some well-known cartridge types supported are "Plus4 multi cart" (size 2 MiB or 4 MiB, using banks of 32 KiB) and "1MB Cartridge" (size 1 MiB with 64 banks of 16 KiB) among others. Each cartridge type has specific load address ranges and banking register behaviors.

Files in this format begin with a header identifying them as PLUS4 cartridge images. The ASCII signature "PLUS4 CARTRIDGE" appears at file offset 0x0000, followed by a structure that encodes the cartridge size, type, and banking configuration. This header allows the VICE emulator to recognize that the image is a PLUS4 cartridge.

VICE VIC20 Cartridge

VICE VIC20 Cartridge files store digital copies of cartridges made for the Commodore VIC-20 computer, used by the VICE emulator. They package read-only ROM or ROM/RAM data from VIC-20 cartridges, including popular plug-in hardware types like Mega-Cart, UltiMem, Final Expansion, Behr Bonz, Super Expander, Vic Flash Plugin, Rabbit tape turbo, Mikro Assembler and Write Now. These cartridge images allow VICE to simulate cartridges in VIC-20 emulation sessions.

The files are created or written by VICE when saving cartridges in its native cartridge image format. Emulation software such as VICE reads the file, parses its header to identify which cartridge hardware type it represents, and maps the cartridge's ROM or RAM banks into the VIC-20's memory map accordingly. In generic cartridge mode, one or more ROM "CHIP" packets are stored; each corresponds to one of the VIC-20's expansion memory blocks (for example at addresses $2000 - $3FFF, $4000 - $5FFF, $6000 - $7FFF, or $A000 - $BFFF). Hardware-specific features such as banking registers and configuration settings are included when needed.

The file begins with a header signature identifying it as a VIC-20 cartridge image. It starts at offset 0 with the ASCII string "VIC20 CARTRIDGE ". The header includes fields for file data size, version number (currently VICE 2.0 spec is version 02.00), cartridge hardware type, and a 32-byte cartridge name (uppercase, null-padded). After the fixed-length header, the file contains CHIP packet data holding the actual content.

Various apps that use files with this extension

These apps are known to open certain types of CAR files. Remember, different programs may use CAR files for different purposes, so you may need to try out a few of them to be able to open your specific file.

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