CHM to XZ Converter
Processing entirely on your device — large files may take a moment.
CHM is Microsoft's compiled help format: HTML topics, images and an index compressed into one legacy-but-everywhere file. Old software manuals, ebooks and documentation still ship as CHM. Unpack XZ into ZIP/TAR for tools that cannot read LZMA2.
Because the whole conversion happens on your device, it is instant, unlimited and genuinely private — no accounts, no watermarks, no files on anyone's server. Multiple files are converted in one go.
How CHM compares to XZ
| CHM | XZ | |
|---|---|---|
| Compression | LZX | LZMA2 |
| Bundling | HTML topics + index in one file | Single file |
| Best for | Legacy software manuals | Packages and releases |
How to convert CHM to XZ
- 1
Select your files
Select your CHM file.
- 2
Convert instantly
The file bytes are gzip-compressed in place — the same archive your server or build tool produces, made locally.
- 3
Download results
Download the .gz file — ready to upload, serve or attach.
About the CHM format
CHM (Compiled HTML Help) is Microsoft's format for bundling HTML topics, images and a searchable index into one file. An entire generation of software manuals, programming references and even novels shipped as CHM — and modern Windows no longer renders it comfortably.
Extracting a CHM gives you back the raw HTML topics and images: open them in any browser, convert them onward to PDF or EPUB, or migrate the content into a modern documentation system. The help tree becomes regular files.
+Strengths
- ✓Unlocks decades of locked-in documentation
- ✓Topics come out as clean, standalone HTML
- ✓No deprecated viewer required
!Limitations
- −Index and search metadata do not convert
- −Topic filenames are often opaque codes
- −Some CHM files use encodings that need care
About the XZ format
XZ wraps the LZMA2 algorithm: the best ratio of the common Unix compressors, which is why distribution packages and source releases pick it when bandwidth matters more than CPU.
Windows Explorer and many cross-platform tools cannot open it — unpacking to ZIP or TAR makes the payload portable.
+Strengths
- ✓Highest common ratio
- ✓Standard for Linux packages
- ✓Integrity checks built in
!Limitations
- −Memory-hungry at high settings
- −Sparse support outside Linux
Why convert CHM to XZ?
Converting makes sense where the strengths of XZ meet what CHM cannot give you. Highest common ratio Meanwhile Index and search metadata do not convert One pass through the converter above puts your file on the right side of that trade-off.
Frequently asked questions
Is this CHM to XZ converter really free?
Yes — completely free, with no sign-up, no watermark and no daily conversion limits. The site is supported by advertising.
Are my files uploaded to a server?
No. The conversion runs entirely inside your browser using WebAssembly, so your files never leave your device — that is what makes it instant and private.
Does it work on Windows, Mac, iPhone and Android?
Yes. Anything with a modern browser works: Windows, macOS, Linux, Android and iOS. No software installation is required.
Is there a file size limit for CHM to XZ?
The only limit is your device's memory, since nothing is uploaded. Files up to a few hundred megabytes work fine on a modern desktop browser; very large files simply take a little longer.
Is there a size limit for archive conversion?
There is no upload cap because nothing is uploaded — the practical limit is your device memory. A few hundred megabytes of unpacked content works comfortably on a modern computer.
Are the files inside my CHM archive modified?
No. Contents are unpacked in memory and repacked into XZ byte-for-byte — the conversion changes the container, never the files inside it.