ARC File

What are ARC files and how to open them

Are you having problems opening an ARC 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 ARC files.

What is an ARC file?

ARC files have multiple uses, and ARC compressed archive is one of them. Read more about the other uses further down the page.

ARC compressed archive

Files that contain the .arc file extension are compressed archive files. An archive file is a batch of files combined into a single file for easier distribution. Compressing the files means they have been reduced in size to save storage space and bandwidth. You will need a "decompressor" tool to access the contents of these files.

The ARC format was invented by System Enhancement Associates (SEA) in the 80s, and you needed their tool, also named "arc", to compress and decompress ARC files.

It is one of the very first predecessors of archive formats like ZIP files. Today, the original ARC format is no longer used, but a range of modern software tools can still decompress these older archive files.

How to open ARC files

We have identified two ARC openers that are compatible with this specific type of ARC file.

Programs that open ARC compressed archive files

Last updated: August 20, 2026

All known file formats using extension .ARC

While ARC compressed archive is a popular type of ARC-file, we know of 10 different uses of the .ARC file extension. Different software may use files with the same extension for different types of data.

FreeArc compressed archive

Some .ARC files are compressed archive files created with FreeArc. An archive file is a set of files bundled into a single file for easier distribution on the internet, and compressing (reducing the size of the file) is done to save bandwidth.

FreeArc was a compression tool that used different compression algorithms depending on each file type in the archive. One algorithm was used to e.g., compress sound files, and other algorithms were used to compress executable files.

Benchmarking showed that FreeArc was able to beat popular programs like WinZip, 7-Zip, and WinRAR regarding compression efficiency. However, the development of FreeArc seems to have stopped, and the official website is no longer online.

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

Internet Archive ARC File Format

Internet Archive, a website preservation service, has its own archive file format using file extension ARC. They use it to store copies of web pages downloaded from the internet.

It uses standard GZIP compression, but stores the files in an interesting way: Instead of compressing a batch of pages into a single compressed archive file, they compress each file with GZIP and concatenate them into a single ARC file. In that way, their tools can search for a specific file inside the ARC file and decompress only that, instead of having to decompress the entire file first. The format is GZIP compatible so that you can treat it as a normal .gz file.

Nintendo Yaz0 Compressed Data

Nintendo ARC files are game data files in their proprietary "Yaz0" format. The Nintendo ARC format is used to compress (reduce in size) game data like 3D models and texture file, to make it possible to fit more data onto a single media like a CD or DVD. They are also commonly seen use the .szs file extension.

ARC opener for Windows

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

ArcMac Compressed Archive

We know that one ARC format is ArcMac Compressed Archive. We have not yet analyzed in detail what these files contain and what they are used for. We're working on it.

BGI/Ethornell Game Engine Data

BGI/Ethornell engine resource archive files hold all the assets a game needs - scripts, images, audio, video, fonts, UI elements - packed together in one container. They are produced by the Buriko General Interpreter (BGI), especially its Ethornell variant, to store everything the engine uses at runtime. The format supports two versions, commonly called PackFile (old version) and BURIKO ARC20 (new version), differing in header magic and index layout.

Each archive begins with a fixed-size header that includes a magic string (either "PackFile " or "BURIKO ARC20") followed by a 32-bit integer for the number of files. That integer determines how many index entries follow. The index area lists each file inside the archive by name, and for each file there is an offset and size measuring where the file's content begins and how large it is. In PackFile version names are 16-byte strings, in ARC20 they tend to be 96-byte filename fields. Padding is used to fill unused name space.

After the index, raw data blobs for each file appear one after the other. Some entries may be compressed or encrypted, especially script files (DSC), images (CBG), or audio (BW). The archive-reading tools will detect inner magic in those blobs ("BSE 1.0", "CompressedBG", "bw ", etc.) and apply decryption or decompression before returning usable data.

Technical identification comes from a "magic" sequence at the very start of the file and the layout of the index. PackFile archives start with the ASCII signature "PackFile " at offset 0; ARC version 2 files begin with "BURIKO ARC20". Index entries for PackFile list filename (16 bytes), offset (32-bit little endian), size (32-bit), then padding; in ARC20 the filename field is much longer (96 bytes) and padding extended accordingly.

EZBIND Archive

We know that one ARC format is EZBIND Archive. We have not yet analyzed in detail what these files contain and what they are used for. We're working on it.

KaGuYa Engine Resource Data

KaGuYa Engine resource data files store game assets (images, sounds, scripts etc.) bundled by the KaGuYa visual novel engine into a custom archive format. They are used by the engine to package all resources needed by a game so that they can be streamed or loaded efficiently at runtime.

These resource data files are written by games made with the KaGuYa engine. They are opened by the same engine during gameplay and can also be parsed, extracted or browsed using specialized tools like GARbro, which treat them as archives and list or extract contained files.

Internally there is a fixed signature at the very start that identifies the format: the ASCII header WFL1 (bytes 0x57464C31) appears at offset 0. After this, the file includes an index of entries which lists each item's name, data offset, size, and mode (indicating whether the item is compressed). If compressed, an unpacked size is also stored. Mode values also determine whether an entry holds audio, image or other types.

Majiro Engine Resource Data

Majiro Engine Resource Data files store collections of game assets - images, sounds, scripts, etc. - packed into a single archive used by the Majiro visual novel engine. They are produced by tools used with Majiro and then read by the game when running, allowing efficient access to many resource files stored together.

These archives organize data so that the file list, names, and content are separated: a header gives the number of entries, where the filenames begin, and where the actual file contents start. An index (or table) lists each file's hash (derived from its name), offset into the data region, and (in newer versions) a length. File names are stored in a names buffer as a sequence of null-terminated strings. All file data appears afterward without compression.

Different versions of the format change how entries are represented: version 1 omits explicit lengths and uses an extra dummy table entry to compute the last file's size; version 2 includes a length field per file; version 3 uses a larger hash (CRC-64) for names. File creation tools compute and sort name hashes, then write the signature ("MajiroArcV1.000", "MajiroArcV2.000", or "MajiroArcV3.000" plus a zero byte), followed by count, offsets, the file entry table, the names buffer, and finally the concatenated data buffer.

At the start of the file appears a 16-byte ASCII signature such as "MajiroArcV1.000" (or V2/V3), followed by a null byte. Immediately after are three unsigned 32-bit (4-byte) values: the number of files, the absolute offset to the names buffer, and the absolute offset to the data buffer. Entry table records follow; for version 1 each record has two uint32 fields (hash, offset), for version 2 three fields (hash, offset, length), and for version 3 hash is uint64 while the other two remain uint32.

Xexor Amstrad disk image

.ARC files created with the Amstrad Xexor disk utility contains a copy of an Amstrad diskette. Amstrad created popular home computers in the 80s, and if you are interested in these legacy computer systems, you may come across these .arc files if you want to play old Amstrad games in an emulator.

You usually do not need to edit or view these files, as they only contain information usable by the software program that uses them.

Various apps that use files with this extension

These apps are known to open certain types of ARC files. Remember, different programs may use ARC 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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