Convert HTML help files (CHM) online for free
The converter easily converts your CHM help files to various formats - free and online. No Microsoft Windows or other E-Book software needed.
To convert other file formats to the "Compiled HTML Help File" file type, you need software like Microsoft Windows or a similar tool.
The .CHM file format is a proprietary help documentation format created by Microsoft. Originally introduced with Windows 98, it packages multiple HTML pages, an interactive index, and embedded images into a single binary archive using LZX compression. You will typically encounter these files as legacy software manuals, offline technical documentation, or older e-books.
To open .CHM files natively, users rely on the built-in Microsoft HTML Help Executable on Windows. You can learn more about the internal architecture on the Microsoft Compiled HTML Help Wikipedia page.
Despite its past popularity, the .CHM format presents significant disadvantages today. Because these files can execute embedded code, they are widely recognized as a severe security risk. Modern email providers and network firewalls frequently block them entirely. Furthermore, Windows itself will often flag downloaded .CHM files as unsafe, resulting in a blank viewer window until the file is manually unblocked in the operating system's properties menu. Reading a .CHM file on a Mac, Linux machine, or mobile device is incredibly frustrating, as it requires installing third-party reader applications due to a total lack of native cross-platform support.
To fix these compatibility and security issues, converting your .CHM file is the most practical solution. For universal sharing, secure emailing, and archiving, convert to PDF. If you intend to read the manual on a mobile device or e-reader, convert to EPUB to maintain reflowable text. To extract the raw contents for web editing, convert to standard HTML. Drag and drop your file here to analyze and convert it - free, online, and without installing software.
Use Convert.Guru to open and convert your CHM file.
Users also converted CHW, HLP, CFM, CSM, CIM, VDOC, CHR, CHT, PDF, GHO, TORRENT, OPF and BIN files.
If you want to convert CHM file to HTML, MARKDOWN, HTM, CSS, JS, PHP, ASP, ASPX or JSP, you can use Microsoft Windows or similar software from the "Software Help Documentation" category. In the File menu, look for Save As… or Export….
To convert RSS, CSS, CGI, SITEMAP, PL, WEBMANIFEST, JSON, JS, XML, HTML, ICO or HTM files to CHM, try Microsoft Windows or another comparable tool in the "Software Help Documentation" category.
The history of Convert.Guru began over 25 years ago in California with Tom Simondi’s file-format database. A former contributor to Space Shuttle development and a software pioneer of the 1980s, Simondi established a trusted resource for file type analysis that was even referenced by Microsoft Windows XP. Today, we use modern technology to process and convert thousands of file formats while continually improving our CHM converter.