This article is about the mhtml webarchive format. For Mason file extension .mhtml, see Mason (Perl)
MHTML, short for MIME HTML, is a web page archive format used to combine resources that are typically represented by external links (such as images, Flash animations, Java applets, audio files) together with HTML code into a single file. The content of an MHTML file is encoded as if it were an HTML e-mail message, using the MIME type
multipart/related. The first part of the file is normally encoded HTML; subsequent parts are additional resources identified by their original URLs and encoded in base64. This format is sometimes referred to as MHT, after the suffix .mht given to such files by default when created by Microsoft Word, Internet Explorer, or Opera. MHTML is a proposed standard, circulated in a revised edition in 1999 as RFC 2557.
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.
Microsoft Internet Explorer, as of version 5.0, was the first browser to support reading and saving web pages and external resources to a single MHTML file.
Support for saving web pages as MHTML files was made available in the Opera 9.0 web browser. Beginning with Opera 9.50, the default format for saving pages is MHTML.
Mozilla Firefox requires an extension to be installed to read and write MHT files. Many such extensions are freely available, two of which are the Mozilla Archive Format and UnMHT.
Although Firefox does not currently (as of version 15.0.1) include support for MHTML without the use of add-ons, there is source code available for viewing MHTML files within the related Thunderbird project, indicating that future support in Mozilla software such as Firefox may become available without such add-ons.
As of version 3.1.1 onwards, Apple Inc.'s Safari web browser does not natively support the MHTML format. Instead, Safari supports the webarchive format, and the OS X version includes a print-to-PDF feature.
As with most other modern web browsers, support for MHTML files can be added to Safari via various third-party extensions.
As of version 3.5.7, KDE's Konqueror web browser does not support MHTML files. An extension project, mhtconv, can be used to allow saving and viewing of MHTML files.
NetFront 3.4 (on devices such as the Sony Ericsson K850) can view and save MHTML files.
Viewing and creating MHTML files in current versions of Google Chrome (23.0) is supported by toggling the "Save Page as MHTML" option on the chrome://flags page. However, enabling this experimental option disables saving pages as HTML-only or HTML Complete files.
There are commercial software products for viewing MHTML files and converting them to other formats, such as PDF.