MHTML

<h2 id="layout">Layout</h2>
<p>The header of an MHTML file contains metadata such as a <a href="/facts/Time_stamp/6lApANE6">date and time stamp</a>, page title, the source URL, and a unique randomized boundary string for separating resources contained within the file. The boundary string is defined at the beginning and used throughout the file.
</p>
From: <Saved by Blink>
Snapshot-Content-Location: https://en.wikipedia.org/wiki/Smartphone
Subject: Smartphone - Wikipedia
Date: Sat, 24 Sep 2022 00:34:32 -0000
MIME-Version: 1.0
Content-Type: multipart/related;
        type="text/html";
        boundary="----MultipartBoundary--GsIBda0vjy2AKIAIliwl7JMwezXDRjDAsLje9khd5l----"

<p>Then, the page resources are contained sequentially, starting with the page's rendered HTML source code. Each resource has its own metadata header which specifies its <a href="/facts/MIME_type/A31N5Fwj">MIME type</a> and the original location.
</p>
------MultipartBoundary--GsIBda0vjy2AKIAIliwl7JMwezXDRjDAsLje9khd5l----
Content-Type: text/html
Content-ID: <frame-D968CEC8BB7E60A1859261A8CA5DFB4D@mhtml.blink>
Content-Transfer-Encoding: binary
Content-Location: https://en.wikipedia.org/wiki/Smartphone

<!DOCTYPE html>

<p>The MHTML file ends with a boundary string that is not followed by any data.<a class="footnote-ref" id="fnref:2" href="#fn:2"><sup>2</sup></a>
</p>
<h2 id="mime-type">MIME type</h2>
<p>MIME type for MHTML is not well agreed upon. Used MIME types include:
</p>
<ul><li>multipart/related</li>
<li>application/x-mimearchive</li>
<li>message/rfc822</li></ul>
<h2 id="supporting-apps">Supporting apps</h2>
<h3>Web browsers</h3>
<p>Some browsers support the MHTML format, either directly or through third-party extensions, but the process for saving a web page along with its resources as an MHTML file is not standardized. Due to this, a web page saved as an MHTML file using one browser may render differently on another.
</p>
<ul><li><a href="/facts/Internet_Explorer_5/HaSYzQEg">Internet Explorer 5</a> was the first browser to support reading and saving web pages and external resources to a single MHTML file.</li>
<li><a href="/facts/Microsoft_Edge/BGoJEFX9">Microsoft Edge</a>, after switching to the Chromium source code, supports saving web pages as MHTML.</li>
<li><a href="/facts/Opera_(web_browser)/2NYCcTj1">Opera</a>: Support for saving web pages as MHTML files was made available in the Opera 9.0 web browser.<a class="footnote-ref" id="fnref:3" href="#fn:3"><sup>3</sup></a> From Opera 9.50 through the rest of the Presto-based Opera product line (version 12.16 as of 19 July 2013), the default format for saving pages is MHTML. The initial release of the new Webkit/Blink-based Opera (version 15) did not support MHTML, but subsequent releases (16 and later) do. MHTML can be enabled by typing "opera://flags#save-page-as-mhtml" at the address bar.</li>
<li><a href="/facts/Google_Chrome/4INfWq37">Google Chrome</a> 86 and later can create MHTML files.</li>
<li><a href="/facts/Yandex_Browser/lqCtwx7z">Yandex Browser</a> 22.7.4.960 (July 2022) and later can create MHTML (multipart/related) files.</li>
<li><a href="/facts/Vivaldi_(web_browser)/RGkUfY7Y">Vivaldi</a> 2.3 and later can create MHTML files.<a class="footnote-ref" id="fnref:4" href="#fn:4"><sup>4</sup></a> It supports both reading and writing MHTML files by toggling the "vivaldi://flags/#save-page-as-mhtml" option.</li>
<li><a href="/facts/Firefox/xez2zv8H">Firefox</a> does not support MHTML.<a class="footnote-ref" id="fnref:5" href="#fn:5"><sup>5</sup></a> Until <a href="/facts/Firefox_version_history/NDTN6qpu">version 57 ("Firefox Quantum")</a>, two <a href="/facts/Browser_extension/jzkeh57V">browser extension</a>, Mozilla Archive Format or UnMHT, could read and write MHTML files. These extensions are incompatible with version 57 and later.</li>
<li><a href="/facts/Safari_(web_browser)/9R8v7tNl">Safari</a> 3.1.1 and later terminated native support for the MHTML format. Instead, the browser supports the <a href="/facts/Web_Archive_(file_format)/vJ1wr19y">Web Archive</a> format. The <a href="/facts/MacOS/Y93vVpTm">macOS</a> version includes a print-to-<a href="/facts/PDF/C9Mn1vYL">PDF</a> feature. As with most other modern web browsers, support for MHTML files can be added to Safari via various third-party extensions.</li>
<li><a href="/facts/Konqueror/qWCwNfur">Konqueror</a> 3.5.7 and later terminated support for MHTML files. An extension project, mhtconv, can be used to allow saving and viewing of MHTML files.</li>
<li><a href="/facts/NetFront/ofXK1vrS">NetFront</a> 3.4 (on devices such as the Sony Ericsson <a href="/facts/K850/Qk39o5pV">K850</a>) can view and save MHTML files.</li>
<li><a href="/facts/Pale_Moon_(web_browser)/8Wye08yN">Pale Moon</a> requires an extension to be installed to read and write MHT files. One extension is freely available, MozArchiver, a fork of Mozilla Archive Format extension.</li>
<li><a href="/facts/GNOME_Web/0hIb10Th">GNOME Web</a> added support for read and save web pages in MHTML since version 3.14.1 released in September 2014.<a class="footnote-ref" id="fnref:6" href="#fn:6"><sup>6</sup></a></li></ul>
<h3>Other apps</h3>
<ul><li><a href="/facts/Problem_Steps_Recorder/MA87E3fj">Problem Steps Recorder</a> for Windows can save its output to MHT format.</li>
<li>The "Save to Google Drive" extension for <a href="/facts/Google_Chrome/4INfWq37">Google Chrome</a> can save as MHTML as one of its outputs.</li>
<li><a href="/facts/Microsoft_OneNote/WleY77sC">Microsoft OneNote</a> 2010 and later can email individual pages as .mht files.</li>
<li><a href="/facts/Evernote/YJMUnxBL">Evernote</a> for Windows can export notes as MHT format, as an alternative to HTML or its own native .enex format.</li></ul>
<h2 id="exploits">Exploits</h2>
<p>In May 2015, a researcher noted that attackers could build malicious documents by creating an MHT file, appending an MSO object at the end (MSO is a file format used by the <a href="/facts/Microsoft_Outlook/cMGCKGFJ">Microsoft Outlook</a> e-mail application), and renaming the resulting file with a .doc extension.<a class="footnote-ref" id="fnref:7" href="#fn:7"><sup>7</sup></a> The delivery method would be by spam emails.<a class="footnote-ref" id="fnref:8" href="#fn:8"><sup>8</sup></a>
</p><p>In April 2019, a security researcher published details about an <a href="/facts/XML_external_entity_attack/psvozzPy">XML external entity (XXE) vulnerability</a> that could be exploited when a user opens an MHT file. Since the Windows operating system is set to automatically open all MHT files, by default, in Internet Explorer, the exploit could be triggered when a user double-clicked on a file that they received via email, instant messaging, or another vector, including a different browser.<a class="footnote-ref" id="fnref:9" href="#fn:9"><sup>9</sup></a>
</p>
<h2 id="alternatives">Alternatives</h2>
<h3>data URI scheme</h3>
<p>The <a href="/facts/Data_URI_scheme/7hBR45J2">data URI scheme</a> offers an alternative for including separate elements such as images,  style-sheets and scripts in-line when serving an HTML request or saving an HTML resource for offline use. Like the embedded content within MHTML, data URIs use <a href="/facts/Base64/xIvVm33q">Base64</a> encoding of the external resources (which may be binary or text) to embed them in-line within the HTML markup. HTML pages saved with external elements embedded using the <a href="/facts/Data_URI_scheme/7hBR45J2">data URI scheme</a> are standard web pages, and can be opened by any modern browser, including browsers not supporting MHTML such as Mozilla Firefox.<a class="footnote-ref" id="fnref:10" href="#fn:10"><sup>10</sup></a> Unlike MHTML, saving web pages with their external resources embedded using data URIs requires a third-party extension to be installed in the browser.<a class="footnote-ref" id="fnref:11" href="#fn:11"><sup>11</sup></a>
</p>
<h3>Mozilla Archive Format</h3>
<p>The <a href="/facts/Mozilla_Archive_Format/zWkf6aeh">Mozilla Archive Format</a> (MAFF) is a legacy Web archive file format that was supported by Firefox from 2004 to 2018 through an add-on.<a class="footnote-ref" id="fnref:12" href="#fn:12"><sup>12</sup></a> Unlike both MHTML and data URIs, MAFF uses a <a href="/facts/ZIP_(file_format)/qDrrYIB9">ZIP</a> container to preserve both the HTML file and its external elements. In October 2017 the add-on developer announced the format would no longer be supported in future versions of Firefox.<a class="footnote-ref" id="fnref:13" href="#fn:13"><sup>13</sup></a>
</p>
<h2 id="see-also">See also</h2>
<ul><li><a href="/facts/Data_URI_scheme/7hBR45J2">data URI scheme</a></li>
<li><a href="/facts/Mozilla_Archive_Format/zWkf6aeh">Mozilla Archive Format</a></li>
<li><a href="/facts/Web_Archive_(file_format)/vJ1wr19y">Web Archive format</a></li>
<li><a href="/facts/WARC_(file_format)/hfmFu021">WARC format</a></li></ul>

<h2 id="external-links">External links</h2>
<ul><li><a href="http://www.dsv.su.se/~jpalme/ietf/mhtml.html">MHTML standard explained</a></li>
<li><a href="https://datatracker.ietf.org/doc/rfc2557/">RFC 2557</a> (1999)—MIME Encapsulation of Aggregate Documents, such as HTML (MHTML)</li>
<li><a href="https://datatracker.ietf.org/doc/rfc2110/">RFC 2110</a> (1997, Obsolete)—MIME E-mail Encapsulation of Aggregate Documents, such as HTML (MHTML)</li></ul>

<h2 id="references">References</h2>

<ol>
<li id="fn:1"><p>Holden, Amanda. "Difference of HTML & MHTML". Archived from the original on 17 November 2017. Retrieved 17 November 2017. <a href="https://web.archive.org/web/20171117122700/https://www.techwalla.com/articles/difference-of-html-mhtml" target="_blank">https://web.archive.org/web/20171117122700/https://www.techwalla.com/articles/difference-of-html-mhtml</a> <a href="#fnref:1" class="footnote-back-ref">↩</a></p></li>
<li id="fn:2"><p>"2. The MHTML File Format - Hunchly Knowledge Base". support.hunch.ly. October 17, 2018. Retrieved 24 September 2022. <a href="https://support.hunch.ly/article/51-1-the-mhtml-file-format" target="_blank">https://support.hunch.ly/article/51-1-the-mhtml-file-format</a> <a href="#fnref:2" class="footnote-back-ref">↩</a></p></li>
<li id="fn:3"><p>Santambrogio, Claudio (10 March 2006). "…and one more weekly!". Opera Software. Archived from the original on 15 January 2010. Retrieved 2009-05-15. <a href="https://web.archive.org/web/20100115001636/http://my.opera.com/desktopteam/blog/show.dml/172375" target="_blank">https://web.archive.org/web/20100115001636/http://my.opera.com/desktopteam/blog/show.dml/172375</a> <a href="#fnref:3" class="footnote-back-ref">↩</a></p></li>
<li id="fn:4"><p>février 6, Publié sur; Tetzchner, 2019-Par Jon von (2019-02-06). "Vivaldi Update | Auto-Stacking Tabs". Vivaldi (in French). Retrieved 2019-05-16.{{cite web}}:  CS1 maint: numeric names: authors list (link) <a href="https://vivaldi.com/fr/blog/auto-stacking-tabs/" target="_blank">https://vivaldi.com/fr/blog/auto-stacking-tabs/</a> <a href="#fnref:4" class="footnote-back-ref">↩</a></p></li>
<li id="fn:5"><p>"Bug 40873 - Save as rfc 2557 MHTML; complete webpage in one file". <a href="https://bugzilla.mozilla.org/show_bug.cgi?id=40873" target="_blank">https://bugzilla.mozilla.org/show_bug.cgi?id=40873</a> <a href="#fnref:5" class="footnote-back-ref">↩</a></p></li>
<li id="fn:6"><p>"NEWS · master · GNOME / Epiphany". 28 July 2023. <a href="https://gitlab.gnome.org/GNOME/epiphany/blob/master/NEWS#L1061" target="_blank">https://gitlab.gnome.org/GNOME/epiphany/blob/master/NEWS#L1061</a> <a href="#fnref:6" class="footnote-back-ref">↩</a></p></li>
<li id="fn:7"><p>Kovacs, Eduard (May 11, 2015). "Attackers Hide Malicious Macros in MHTML Documents". SecurityWeek.Com. Retrieved April 19, 2019. <a href="https://www.securityweek.com/attackers-hide-malicious-macros-mhtml-documents" target="_blank">https://www.securityweek.com/attackers-hide-malicious-macros-mhtml-documents</a> <a href="#fnref:7" class="footnote-back-ref">↩</a></p></li>
<li id="fn:8"><p>Mosuela, Lordian (July 10, 2015). "New Tricks of Macro Malware". Cyren. Retrieved April 19, 2019. <a href="https://www.cyren.com/blog/articles/new-tricks-of-macro-malware" target="_blank">https://www.cyren.com/blog/articles/new-tricks-of-macro-malware</a> <a href="#fnref:8" class="footnote-back-ref">↩</a></p></li>
<li id="fn:9"><p>Cimpanu, Catalin (April 12, 2019). "Internet Explorer zero-day lets hackers steal files from Windows PCs". ZDNet. Retrieved April 19, 2019. <a href="https://www.zdnet.com/article/internet-explorer-zero-day-lets-hackers-steal-files-from-windows-pcs/" target="_blank">https://www.zdnet.com/article/internet-explorer-zero-day-lets-hackers-steal-files-from-windows-pcs/</a> <a href="#fnref:9" class="footnote-back-ref">↩</a></p></li>
<li id="fn:10"><p>"Data URLs - HTTP". MDN. Retrieved April 2, 2023. <a href="https://developer.mozilla.org/en-US/docs/Web/HTTP/Basics_of_HTTP/Data_URLs#browser_compatibility" target="_blank">https://developer.mozilla.org/en-US/docs/Web/HTTP/Basics_of_HTTP/Data_URLs#browser_compatibility</a> <a href="#fnref:10" class="footnote-back-ref">↩</a></p></li>
<li id="fn:11"><p>Brinkmann, Martin (September 3, 2018). "Save any webpage as a single file in Chrome or Firefox - gHacks Tech News". ghacks.net. Retrieved April 2, 2023. <a href="https://www.ghacks.net/2018/09/03/save-any-webpage-as-a-single-file-in-chrome-or-firefox/" target="_blank">https://www.ghacks.net/2018/09/03/save-any-webpage-as-a-single-file-in-chrome-or-firefox/</a> <a href="#fnref:11" class="footnote-back-ref">↩</a></p></li>
<li id="fn:12"><p>"Mozilla Archive Format Add-on - File Format Overview". amadzone. Retrieved April 2, 2023. <a href="https://www.amadzone.org/mozilla-archive-format/" target="_blank">https://www.amadzone.org/mozilla-archive-format/</a> <a href="#fnref:12" class="footnote-back-ref">↩</a></p></li>
<li id="fn:13"><p>"Firefox Addon: MAF - Mozilla Archive Format". Archived from the original on 2 November 2017. Retrieved 2 April 2023. <a href="https://web.archive.org/web/20171102005204/https://addons.mozilla.org/en-US/firefox/addon/mozilla-archive-format/" target="_blank">https://web.archive.org/web/20171102005204/https://addons.mozilla.org/en-US/firefox/addon/mozilla-archive-format/</a> <a href="#fnref:13" class="footnote-back-ref">↩</a></p></li>
</ol>

MHTML open-in-new

MHTML