CHM to BZ2 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. Convert BZ2 to ZIP or TAR when modern tools need a friendlier container.
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 BZ2
| CHM | BZ2 | |
|---|---|---|
| Compression | LZX | BWT + Huffman |
| Bundling | HTML topics + index in one file | Single file |
| Best for | Legacy software manuals | Large text dumps |
How to convert CHM to BZ2
- 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 BZ2 format
BZ2 applies the Burrows–Wheeler transform: slower than gzip but noticeably smaller, which is why Wikipedia database dumps and old source tarballs still arrive as .bz2.
Few GUI tools ship a bz2 reader these days, so converting the contents into a ZIP or TAR is the practical way to hand the payload to someone else.
+Strengths
- ✓Better ratio than gzip
- ✓Common in dumps and archives
- ✓Mature, stable format
!Limitations
- −Slow to compress and decompress
- −Declining tool support
Why convert CHM to BZ2?
Think of it as moving your file to the container that fits the job. Index and search metadata do not convert BZ2 works differently: Better ratio than gzip If any of that sounds like your task, run the conversion — it takes seconds and nothing leaves your device.
Frequently asked questions
Is this CHM to BZ2 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 BZ2?
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.
Are the files inside my CHM archive modified?
No. Contents are unpacked in memory and repacked into BZ2 byte-for-byte — the conversion changes the container, never the files inside it.
What about folders and directory structure?
The full directory tree is preserved: folders stay folders, and deep paths arrive exactly as they were packed in the CHM file.