.OTH file extension

To open .OTH files on Windows, install or use an ODF-compatible office suite that supports OpenDocument templates (for example, LibreOffice).

To open a .OTH file, use an ODF-compatible office suite that supports OpenDocument templates (for example, LibreOffice). If it won’t open on mobile, transfer it to a desktop app that can handle ODF templates.

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Last updated: June 11, 2026 · Reviewed by Julian Stricker

What “reviewed” means on this page

Format fit: whether the “what is this file?” description matches common real-world use of the extension, including category, typical MIME types, and aliases.
Opening paths: whether Windows / macOS / Linux steps read plausibly for current OS dialogs and default apps; we remove fantasy menus and unsafe shortcuts.
Security framing: whether risk notes match the extension class (for example executables vs plain data) and whether affiliate wording does not contradict the security section.
Sources and further reading: whether external links point to vendors, standards bodies, or other primary references where possible; we avoid inventing details we cannot ground.
Limits: this is clarity and safety-messaging QA, not a guarantee that every statement is exhaustive or that every binary you download is harmless.

Full methodology in the Imprint — The Imprint also states where AI is used and what that does—and does not—replace.

Open on your device

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

How to open .OTH files

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

Windows

Install or use an ODF-compatible office suite that supports OpenDocument templates (for example, LibreOffice).
Right-click the .OTH file → Open with → choose the office suite.
If it opens as a new document, use Save As to create your own copy in the desired format (keeping the original template unchanged).

Full Windows guide

Mac

Install or use an ODF-compatible office suite that supports OpenDocument templates (for example, LibreOffice).
Control-click the .OTH file → Open With → select the office suite.
If you need an editable document copy, create a new document from the template and then Save As.

Full Mac guide

Linux

Open the file in an ODF-compatible office suite (for example, LibreOffice).
If double-clicking doesn’t work, use your file manager’s Open With option and select the office suite.
If your desktop environment misidentifies the file type, check that shared-mime-info mappings are up to date and try again.

Full Linux guide

iOS

iOS often cannot reliably open ODF template types like .OTH in a native preview; transfer the file to a desktop ODF-compatible office suite (for example, LibreOffice) to open or convert it.

Full iOS guide

Android

Android support for ODF template types like .OTH varies; if the file won’t open in your installed office apps, transfer it to a desktop ODF-compatible office suite (for example, LibreOffice) to open or convert it.

Full Android guide

Security notes

.OTH is an ODF package; like other complex document formats, it relies on parsers in office software—only open files from sources you trust, especially if the file is unexpected.
Treat .OTH templates as potentially sensitive: templates can embed reusable content and metadata that may expose internal names, styling choices, or other document context when shared.
If your office suite offers options to disable external content loading (such as linked resources), consider doing so for untrusted templates to reduce the risk of unwanted network access during open.

If you did not expect this file

This extension is usually plain data, text, or structured content—not a program by itself. The practical risk is social engineering (a scam attachment or misleading filename). For trusted senders you rarely need heavy-handed antivirus wording; use these tools when you want an extra check on unexpected downloads.

Avast

Avast offers free and premium antivirus software that protects against viruses, malware, ransomware, and phishing. Scan files before opening them to ensure safety.

Norton

Norton 360 delivers comprehensive antivirus protection, VPN, and identity theft monitoring. Scan files for threats before opening to keep your device secure.

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Can't open this file?

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

Common reasons

The .OTH file won’t open or shows “unknown format”
It opens as a new untitled document instead of the template file
The file appears corrupted or cannot be parsed
Wrong app keeps opening .OTH by default

Fix steps

Open the file from within an ODF-compatible office suite (for example, LibreOffice) instead of relying on double-click associations.
On Linux, ensure your system’s MIME database (shared-mime-info) is updated so .oth is mapped correctly.
If possible, try opening on another desktop system with an ODF-capable suite to confirm it’s not device-specific.

OS-specific troubleshooting

What is a .OTH file?

.OTH is an OpenDocument “text-web” template type (often described as an HTML document template) within the ODF family. Technically, it is an ODF package that includes a required internal mimetype string identifying it as application/vnd.oasis.opendocument.text-web. It is intended to be used as a template (starting point) for creating new web/HTML-oriented documents rather than as a final exported webpage.

Background

The .OTH extension is most commonly associated with the OpenDocument Format (ODF) web page template type, sometimes described in office-suite documentation as an “HTML Document Template.” It is part of the broader ODF ecosystem, which standardizes how office documents and templates are packaged and identified.

Common MIME types: application/vnd.oasis.opendocument.text-web

Common .OTH issues

The .OTH file won’t open or shows “unknown format”

This typically happens when the installed app doesn’t support OpenDocument template types (specifically the ODF text-web template) or the file association is missing.

Open the file from within an ODF-compatible office suite (for example, LibreOffice) instead of relying on double-click associations.
On Linux, ensure your system’s MIME database (shared-mime-info) is updated so .oth is mapped correctly.
If possible, try opening on another desktop system with an ODF-capable suite to confirm it’s not device-specific.

It opens as a new untitled document instead of the template file

Many office suites treat templates as a basis for creating a new document, so they open the template by generating a new document instance.

Use Save As to save the new document under a different name and keep the original .OTH unchanged.
If you need to edit the template itself, look for an option like “Edit Template” or open it from within the application’s template manager (behavior varies by suite).

The file appears corrupted or cannot be parsed

ODF files are packaged formats and can fail to open if the download is incomplete or the internal package structure (including the mimetype entry) is damaged.

Re-download or re-copy the file from the original source and try again.
Try opening it in a different ODF-compatible application to rule out a single-app parsing issue.

Wrong app keeps opening .OTH by default

Your OS may associate .oth with an incorrect application, especially if MIME/extension mappings were changed.

Change the default app association for .oth to your ODF-capable office suite in system settings.
On Linux desktops, refresh/update shared-mime-info and re-log if associations don’t update immediately.

FAQ

What does .OTH stand for and what is it used for?

.OTH is the OpenDocument “text-web” template type, often described as an HTML document template. It’s used as a reusable template to create web-style documents in ODF-compatible office suites.

Is there an official MIME type for .OTH?

Yes. The registered media type for ODF web page templates such as .oth is application/vnd.oasis.opendocument.text-web.

Can I convert a file to .OTH by renaming the extension?

No. Renaming only changes the filename. To create a real .OTH, use an application that can save/export an OpenDocument text-web template.

Why won’t my phone open a .OTH file?

Mobile apps and built-in viewers often have limited support for ODF template subtypes. If it fails to open, use a desktop ODF-compatible suite (for example, LibreOffice) to open or convert it to a more widely supported format.

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