Have you ever saved a web page for offline reading or sharing, and noticed it got saved as a file with the extension .mhtml or .mht? If so, you’ve come across a file format that’s been around for quite some time but still remains relatively unknown to many users. Despite its low profile, MHTML is a compact and useful way to store complete web content in one convenient file.

TL;DR

MHTML, short for MIME HTML, is a file format used to save entire web pages—including images, styles, and scripts—in a single file. It’s supported by some major browsers and can be handy for archiving or sharing web content offline. While not as widely used today due to evolving technologies, it still serves as a useful format for preserving web snapshots. However, compatibility issues and limited browser support can sometimes be drawbacks.

What Exactly Is MHTML?

MHTML stands for MIME HTML, which means that it combines web page content using MIME encoding—similar to the method used in email messages that include attachments. This makes it possible to encapsulate not just the HTML content of a page, but also related resources such as graphics, stylesheets, Flash files (back in the day), and JavaScript files.

The resulting file is a single archive of the entire page, which is convenient for both storage and sharing. MHTML files typically carry a .mht or .mhtml file extension.

How Does It Work?

When you save a webpage as an MHTML file, your browser gathers all the elements that make up the page—text, layout, images, stylesheets, and scripts—and bundles them using the MIME encoding standard. This process is similar to how email clients bundle images and documents with your message into one consolidated file.

The end result is a much more efficient single-file version of a web page, which means you don’t end up with a folder full of images and other assets like you would when saving a page as “Web Page, Complete”.

Here’s a simplified breakdown of what’s included in an MHTML file:

• HTML source code — The page’s actual structure and content.
• Images — Typically encoded as base64 and embedded into the file.
• CSS and JavaScript — Any style or behavior rules embedded in the page.
• Metadata — Headers and flags that define how to treat each resource.

Benefits of Using MHTML

Users and developers might find MHTML useful for a number of reasons:

• Offline Access: Since everything is packed into one file, MHTML can be easily opened without an internet connection.
• Convenient Sharing: Sending one file is generally much easier than sending an HTML file alongside a folder of resources.
• Archiving Content: MHTML is a good format for archiving web pages with a fixed appearance and functionality.
• Reduced File Clutter: There’s no need for additional directories or linked resources.

This format is particularly useful for documentation, legal archiving, and educational content where consistency in layout and visuals must be preserved without reliance on active web hosting.

Where Is MHTML Used Today?

While not at the forefront of modern web usage, MHTML still finds its way into business environments, specialized documentation tools, and browsers with offline or snapshot saving capabilities.

Some common use cases include:

• Browser offline saving: Older versions of Internet Explorer and current versions of Microsoft Edge (via extension or settings) allow saving pages in MHTML.
• Forensics and legal archiving: Law firms and corporate auditors sometimes save pages in MHTML format to retain a copy of web content on a specific date.
• Web research collection: Academics and researchers use MHTML files to save and reference content that might change or be taken down later.

Browser Support: A Mixed Bag

One of the biggest issues with MHTML is its inconsistent browser support. While Internet Explorer supported the format natively for years, modern browsers vary:

• Google Chrome: MHTML support is available but disabled by default. You have to enable it via a flag (chrome://flags).
• Microsoft Edge: Based on Chromium, Edge inherits Chrome’s capabilities but still needs settings tweaks to enable MHTML saving.
• Mozilla Firefox: Does not support MHTML natively. Add-ons or workaround tools are needed.
• Safari: Has no support for MHTML.

How to Open and Create MHTML Files

Opening an MHTML file is fairly straightforward if you have the right tools. Here are your options:

• Web browsers: Internet Explorer, Edge with settings tweaks, and Chrome (with flags enabled) can natively open .mht/.mhtml files.
• Microsoft Word: Surprisingly, Word can open MHTML files and preserve formatting quite well.
• Email clients: Since MIME encoding is similar across MHTML and email, some clients like Outlook can view MHTML content.
• Special software: Tools like MHT Viewer or third-party browsers might help if native support is missing.

To create one, simply go to your browser’s Save option and select “Webpage, Single File” (or similar wording depending on the browser). You may need to enable the proper settings, as mentioned earlier.

Alternatives to MHTML

Due to the limited and inconsistent support across platforms, MHTML is often replaced or supplemented with alternative formats, such as:

• PDF: Very popular for preserving page content along with layout. Nearly universally supported.
• WebArchive (Apple): Used by Safari to save pages, but only opens on Apple devices.
• SingleFile extension: A browser add-on that saves web pages in a single HTML file.
• Screenshot tools: For visual references only, screenshots can serve as lightweight alternatives.

Compared to these, MHTML offers a more complete, editable snapshot of a page—ideal in situations where interactivity or embedded scripts matter.

Security Concerns

A notable downside of the MHTML format stems from its versatility—the ability to embed JavaScript and other scripts in an MHTML file has raised concerns around malware distribution and phishing attacks. Because an MHTML file can contain executable code, some email clients and antivirus programs flag these files as suspicious.

Users should be cautious when opening an unfamiliar .mht file, especially one sent via email or downloaded from an unknown source.

Will MHTML Survive the Test of Time?

The future of MHTML is uncertain; as web apps continue to evolve and browsers push for more secure, sandboxed methods of saving offline data, formats like MHTML could lose relevance. But for now, it still serves a niche group of users who need to maintain interactive and complete versions of web pages.

Its simplicity, self-contained nature, and ability to keep hyperlinks, styles, and scripts make it useful even in the face of more modern alternatives.

Conclusion

MHTML may not be a household name, but its utility shouldn’t be underestimated. Whether you’re archiving legal documents, saving academic research, or just want a reliable format for viewing pages offline, MHTML delivers a complete snapshot of a web page in one single file. That said, its limitations in browser support and security concerns make it something to use with care.

While its prominence may dwindle as newer solutions arise, the MHTML format remains a noteworthy player in the online-to-offline world of content saving.