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.DMS file extension

To open .DMS files on Windows, identify it as an Amiga DMS disk image; if you expected a document, confirm the file’s source and what program created it.

To open a .DMS file, treat it as an Amiga Disk Masher System compressed disk image: first decompress it (commonly with the xdms tool), then load the extracted disk image in an Amiga emulator. If your .DMS came from a game/demo archive, this is the most likely meaning of the extension.

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Last updated: April 30, 2026 · Reviewed by Julian Stricker

Open on your device

Choose your operating system for a dedicated step-by-step opening guide.

How to open .DMS files

Use these platform-specific instructions to open .DMS files safely.

Windows

  1. Identify it as an Amiga DMS disk image; if you expected a document, confirm the file’s source and what program created it.
  2. Use a DMS-capable tool (commonly the xdms decompressor, typically used via command line in a compatible environment) to extract the disk image from the .DMS file.
  3. Open the extracted disk image in an Amiga emulator (see the software suggestions referenced by FileInfo).
Full Windows guide

Mac

  1. Treat .DMS as an Amiga DMS compressed disk image; macOS usually won’t open it directly as a document.
  2. Decompress the file using a DMS decompressor such as xdms (command line), producing a disk image file.
  3. Load the extracted disk image into an Amiga emulator (see the software suggestions referenced by FileInfo).
Full Mac guide

Linux

  1. Install/use a DMS decompressor (for example, xdms) and run it on the .DMS file to extract the disk image.
  2. If extraction succeeds, open the resulting disk image with an Amiga emulator (see the software suggestions referenced by FileInfo).
Full Linux guide

iOS

  1. iOS generally cannot use .DMS files directly; transfer the file to a desktop system and decompress it (e.g., with xdms), then use an Amiga emulator there.
Full iOS guide

Android

  1. Android generally cannot use .DMS files directly; move the file to a desktop system to decompress it (e.g., with xdms) and then open the extracted disk image in an Amiga emulator.
Full Android guide

Security notes

  • A .DMS is an archive-like container for disk contents; once extracted and used in an emulator, it may contain executable Amiga programs. Only run software from sources you trust.
  • Be cautious with unknown .DMS files: decompression tools and emulators must parse complex binary data, so prefer well-maintained tools and avoid files from untrusted sites.
  • If a .DMS file requests a password or displays a notice during extraction, treat it as a sign you should verify authenticity and intent before proceeding.

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Can't open this file?

These are the most common causes and fixes when .DMS files fail to open.

Common reasons

  • The .DMS file won’t open like a document
  • Extraction fails (password/notice or corrupt download)
  • You extracted a file but don’t know how to use it

Fix steps

  1. Verify where the file came from (e.g., an Amiga game/demo archive strongly suggests a DMS disk image).
  2. Use a DMS decompressor (such as xdms) to extract the disk image instead of using a document app.
  3. After extraction, open the disk image in an Amiga emulator (software options are listed by FileInfo).

OS-specific troubleshooting

What is a .DMS file?

.DMS (Disk Masher System) is a compressed disk image format associated with the Amiga ecosystem. It stores floppy-disk data in a compressed form, and is typically decompressed to a usable disk image before being mounted/used in an emulator. Some DMS files may include notices or require a password during extraction, depending on how they were created.

Background

The most common real-world use of .DMS is as a Disk Masher System (DMS) compressed disk image, historically used for distributing Amiga floppy disk contents in a smaller file. The format is closely tied to Amiga software sharing and preservation workflows, where users decompress .DMS files and then load the resulting disk image into an emulator.

Common MIME types: text/vnd.DMClientScript

Further reading

Authoritative resources for more details on the .DMS format.

Common .DMS issues

The .DMS file won’t open like a document

Many .DMS files are not documents at all; they are Amiga DMS compressed disk images. Trying to open them in a document editor/viewer will fail.

  1. Verify where the file came from (e.g., an Amiga game/demo archive strongly suggests a DMS disk image).
  2. Use a DMS decompressor (such as xdms) to extract the disk image instead of using a document app.
  3. After extraction, open the disk image in an Amiga emulator (software options are listed by FileInfo).

Extraction fails (password/notice or corrupt download)

Some DMS images may be created with a notice or password requirement, and extraction can also fail if the file is incomplete or damaged.

  1. Re-download or re-copy the file to rule out corruption/truncation.
  2. If prompted for a password/notice, follow the instructions included with the file/source; if you do not trust the source, stop and do not proceed.
  3. Try extracting with a known DMS tool (e.g., xdms) and review its error output for clues.

You extracted a file but don’t know how to use it

After decompression, you usually get a disk image intended for use in an Amiga emulator rather than a regular desktop file you can open directly.

  1. Check the extractor output to see what file was produced (the extracted disk image is what you load).
  2. Open the extracted disk image in an Amiga emulator (see FileInfo for examples of software that can use DMS images).

FAQ

Is .DMS a document format?

Despite names like “DMS Document File” in some catalogs, the most widely documented use of .DMS is Disk Masher System compressed disk images for Amiga. If your file came from an Amiga software archive, it is almost certainly a disk image, not a document.

How do I open a .DMS file?

Decompress it with a DMS decompressor (commonly xdms), then open the extracted disk image in an Amiga emulator.

Can I convert .DMS by renaming the extension?

No. Renaming does not decompress or transform the data. You must properly extract the disk image with a DMS tool.

Why do some sites mention a MIME type for .DMS?

The extension has multiple associations in the wild. IANA registers the media type text/vnd.DMClientScript, which some lists map to .dms, but that is separate from Amiga Disk Masher System disk images.

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