MHTML

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 was the first browser to support saving web pages with all their resources to a single MHTML file as of its version 5.0 released in 1999.

Support for saving a web page with its resources as an MHTML file was made available in the Opera 9.0 web browser.^[1] In Opera 9.50, the default saving format for the "Save as" function is MHTML.

Mozilla Firefox requires an extension to be installed to read and write MHT files. MAFF [1] and UnMHT [2] are examples. The MAFF and UnMHT extensions were formerly (in 2006) reported to have compatibility issues with opening files saved by them in Internet Explorer.^[2]

Files that are totally compatible with Internet Explorer and other browsers are created by versions 0.14 and later of the maf extension.^{[3] [4] [5]} Internet Explorer-created MHT files render perfectly, and rendering of the divergent Opera-created MHT files has been gradually improved.^{[3] [6] [5]}
UnMHT (version 5.0.0 or greater) offers partial support for MHT files exported from Microsoft Office applications.

Although Firefox does not currently (v12.0) 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. MHTML support has been filed as an unsolved issue within the Firefox project since 1999,^[7] while progress in fixing it seems to be slow moving.

As of version 3.1.1 (released 2008年05月28日) 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 Firefox, a port of UnMHT is available for versions before Safari 5.^[8] It is based on the SIMBL application enhancement loader^[9] and GreaseKit.^[10] Both the SIMBL and GreaseKit solutions must be loaded locally to use UnMHT. However, a sleeker single application called NinjaKit also supports .js scripts for Safari 5+ and can quickly install the same GreaseMonkey-supported files for earlier versions of Safari.

As of version 3.5.7 (released 2007年05月02日), KDE's Konqueror web browser does not support MHTML files. (There is a side project mhtconv that lets one use MHTML with Konqueror for both 3.x and 4.x KDE branches).

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 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.

All versions of Microsoft Word since Word 2002 can open and save MHTML documents.^{[11] [12]} A converter is available from Microsoft to enable Word 2000 to open MHTML files,^[13] and an add-on is available to allow it to save MHTML files.^[14]

MHTML is also supported by Microsoft Office Viewers^{[15] [16]} in Microsoft Word, Microsoft Publisher, Microsoft Excel, and Microsoft PowerPoint.^[17] Microsoft's HTML editors, such as FrontPage, Expression Web, and SharePoint Designer, do not support editing MHTs.

A Windows application called Blocknote supports editing MHTs.^[18]

On the Linux platform, a utility called kmhtConvert is available to convert MHTML files to the KDE Web Archive format.^[19]

• Mozilla Archive Format
• Webarchive
• An alternative for attaching resources to an HTML document is the data URI scheme defined in IETF standard RFC 2397.
  • This method is used by Chrome's SingleFile extension.

• MHTML standard explained
• RFC 2557 (1999) — MIME Encapsulation of Aggregate Documents, such as HTML (MHTML)
• RFC 2110 (1997, Obsolete) — MIME E-mail Encapsulation of Aggregate Documents, such as HTML (MHTML)
• MHT-rip — A program to view MHTML files on Linux

• Internet Explorer
• Archive formats
• HTML

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