.FB file extension

To open .FB files on Windows, check with the sender which application created the .fb file (it is commonly tied to Adobe FrameMaker/Maker workflows).

To open a .fb file, try Adobe FrameMaker (or a FrameMaker-compatible workflow if you have one). On mobile platforms there is usually no dedicated support, so you’ll typically need to move the file to a desktop system to view or convert it.

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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 .FB files

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

Windows

Check with the sender which application created the .fb file (it is commonly tied to Adobe FrameMaker/Maker workflows).
If you have Adobe FrameMaker (or the relevant FrameMaker/Maker toolchain), open the application first and use File → Open to select the .fb file.
If double-clicking fails, right-click the file → Open with… and choose the FrameMaker-related application you use for this workflow.

Full Windows guide

Mac

Confirm with the sender which FrameMaker/Maker-related application produced the .fb file.
Open the file from inside your FrameMaker/Maker-compatible application (File → Open) rather than relying on Finder’s default association.
If macOS says there is no app, you will likely need to open/convert it on a Windows or Linux desktop where your workflow tools are available.

Full Mac guide

Linux

Try opening the .fb file using the same FrameMaker/Maker workflow tools used to create it (if available in your environment).
If your desktop environment does not recognize .fb, open it from within the application (File → Open) instead of double-clicking.
If your distribution does not map .fb to application/x-maker, you may need to configure file associations manually or handle it on another system.

Full Linux guide

iOS

iOS typically won’t recognize .fb: save it in Files, then transfer it to a desktop (Windows/macOS/Linux) that has the appropriate FrameMaker/Maker software to open or convert it.

Full iOS guide

Android

Android may label .fb as application/x-maker in some cases, but you usually still need a desktop FrameMaker/Maker workflow to open it; transfer the file to a desktop system to view/convert it.

Full Android guide

Security notes

Treat .fb as a specialized document type: only open it in trusted, up-to-date applications because document parsers can be a target for malformed-file exploits.
Be cautious with .fb files received unexpectedly by email or chat; the non-standard application/x-maker labeling can cause gateways to misclassify the content type.
Avoid changing system-wide MIME/type mappings for .fb unless you understand the impact, since non-standard types like application/x-maker may affect how other tools handle downloads and attachments.

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Can't open this file?

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

Common reasons

No app can open the .fb file
The file is misidentified or downloads with the wrong type
Opens as text or gibberish in a generic editor

Fix steps

Ask the sender what program exported/created the .fb file and use that same toolchain to open it.
Open the file from inside the relevant application (File → Open) rather than relying on double-click associations.
If you are on mobile, move the file to a desktop system and convert/export it there (for example to PDF) if you only need to read it.

OS-specific troubleshooting

What is a .FB file?

.fb is a file extension that appears in MIME mappings for the FrameMaker/Maker family, commonly labeled with the non-standard media type application/x-maker. It is not an IANA-registered media type, so OS and apps may not recognize it consistently. In practice, how it opens depends on the specific FrameMaker/Maker toolchain that produced it.

Background

In many environments, .fb is treated as part of the Adobe FrameMaker/Maker ecosystem. Multiple software stacks and documentation sets map the extension to the legacy/non-standard MIME type application/x-maker, which is commonly associated with FrameMaker-related content.

Because application/x-maker is not registered in the IANA media types registry, support can vary by platform and distribution. For example, some systems may include the mapping (or have included it historically), while others may omit or remove it, which can affect how browsers, mail clients, or file managers classify .fb files.

If you received a .fb file, it is often best handled on a desktop system where you can use the originating authoring workflow (commonly FrameMaker-related) to open, export, or convert it into a more portable format (such as PDF) if needed.

Common MIME types: application/x-maker

Common .FB issues

No app can open the .fb file

Many systems do not ship with a default handler for .fb, and the commonly associated MIME type (application/x-maker) is non-standard and not consistently supported.

Ask the sender what program exported/created the .fb file and use that same toolchain to open it.
Open the file from inside the relevant application (File → Open) rather than relying on double-click associations.
If you are on mobile, move the file to a desktop system and convert/export it there (for example to PDF) if you only need to read it.

The file is misidentified or downloads with the wrong type

Because application/x-maker is not an IANA-registered media type, servers, browsers, and mail systems may label or handle it inconsistently.

If you manage the server/mail gateway, verify how it maps .fb (some platforms map it to application/x-maker).
If the file arrives renamed or without the .fb extension, restore the original extension and open it from within the correct FrameMaker/Maker application.
If a Linux distribution lacks the mapping, consider adding a local file association to help your desktop environment recognize it.

Opens as text or gibberish in a generic editor

A .fb file tied to a specialized authoring workflow may not be meant for plain-text viewing, so text editors may show unreadable output.

Do not edit it in a text editor unless you know it is text-based in your specific workflow.
Use the appropriate FrameMaker/Maker application to open or export it to a reader-friendly format.
If you only need to share content, request a PDF or another interchange format from the sender.

FAQ

Is .fb an officially registered media type?

The commonly associated type application/x-maker is not an IANA-registered media type, so it is considered non-standard and may not be recognized consistently across systems.

Why does my phone/tablet not open .fb files?

Mobile platforms typically lack FrameMaker/Maker workflow applications. In most cases you’ll need to transfer the file to a desktop system and open or convert it there.

Can I fix it by renaming .fb to another extension?

No. Renaming rarely converts the underlying format. Use the application that created the file (or that workflow) to export/convert it to a different format.

Why does one Linux system recognize .fb but another doesn’t?

Some platforms/distributions include or exclude the application/x-maker mapping. Since it’s non-standard, behavior varies depending on the MIME database and desktop environment configuration.

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