BZ2 to GZ Converter
FileFlip converts BZ2 to GZ entirely inside your browser, using libarchive compiled to WebAssembly. The file is never uploaded to a server: it is read off your disk, converted on your own machine, and saved back by the browser. That means no file-size limit, no queue and no account.
How do I convert a BZ2 file to GZ?#
- Drop your BZ2 file onto the converter at the top of this page, or click it to pick one from your computer. You can add as many as you like.
- Leave the target set to GZ and the conversion starts on its own. FileFlip downloads 1.0 MB of WebAssembly the first time and nothing after that, then runs libarchive on your own machine.
- Save the GZ file. Your browser writes it straight to your downloads folder, because there was never a server holding it.
Does converting BZ2 to GZ lose quality?#
No. Converting BZ2 to GZ does not touch the files inside the archive. Each member is read out and written back byte for byte, so only the wrapper around them changes and nothing is recompressed.
Is it safe to convert BZ2 files online?#
Yes, because nothing is uploaded. FileFlip converts BZ2 files inside the browser tab you already have open, using WebAssembly builds of the same engines a desktop converter would install. Your file is read from your own disk into the page's memory, and no request carrying it is ever made.
You do not have to take that on trust. Open your browser's network panel, run a conversion, and you will see the engine come down and your file go nowhere. There is no upload, no server-side copy, no retention window, and no account tied to what you converted.
How FileFlip works lists every engine, its version and its download size, and shows how to check for yourself that nothing leaves your machine.
What BZ2 to GZ actually does to the file#
Converting BZ2 to GZ runs on libarchive, downloads 1.0 MB of WebAssembly the first time and nothing after that, copies the archived files through unchanged, keeps file contents.
| Engine | libarchive |
|---|---|
| Conversion path | 2 steps: BZ2 → the unpacked files → GZ |
| Downloaded to your browser | 1.0 MB, once, then cached by your browser |
| Quality | Lossless, contents copied unchanged |
| You get back | One file |
| Where it runs | In a background worker, so the page stays responsive |
What survives the conversion
| What is in the file | This conversion | Why |
|---|---|---|
| File contents | Kept | Carried through into the converted file. |
| File timestamps | Sometimes | Survives for some files and not others. |
| File permissions | Sometimes | Survives for some files and not others. |
Worth knowing before you start:
- the output is a PAX tar archive inside the compressor, not a single compressed stream
- every entry is extracted into memory before anything is written, so a very large archive can exhaust it
What is a BZ2 file?#
A BZ2 file is a single stream compressed with Julian Seward's bzip2, which sorts each 100-900 KB block through a Burrows-Wheeler transform before Huffman coding it, trading compression speed for a smaller result than DEFLATE typically achieves.
Use BZ2 for text-heavy data where its tighter compression than gzip is worth the slower compression time.
Convert BZ2 to XZ when an even smaller archive is worth the additional compression time, or to GZ when compression speed matters more than ratio.
What is a GZ file?#
A GZ file wraps a single DEFLATE-compressed stream in a header that can carry the original filename and modification time, plus a trailing CRC-32 checksum, as defined in RFC 1952.
Use GZ to compress a single file quickly, especially one going over HTTP, where gzip decoding is effectively free.
Convert GZ to XZ when the same data needs to be as small as possible and slower compression is an acceptable cost.
BZ2 to GZ questions people ask#
Is bzip2 better than gzip?
bzip2 usually compresses noticeably smaller than gzip, especially on text, because its Burrows-Wheeler transform finds redundancy that DEFLATE misses. The cost is speed: bzip2 compression is markedly slower and needs more memory, sometimes cited at up to four times gzip's.
Can bzip2 hold more than one file?
No, bzip2 compresses a single file or stream just like gzip, so archiving several files as .bz2 means tarring them first into a .tar.bz2, or .tbz2.
Why does bzip2 compress in blocks?
bzip2 splits its input into blocks of 100 KB to 900 KB and runs the Burrows-Wheeler transform, move-to-front coding and Huffman coding on each block independently. That block structure is also what lets tools like pbzip2 compress a bzip2 file's blocks in parallel across multiple CPU cores.
Is bzip2 still worth using over xz?
For most jobs, no: xz built on LZMA2 usually compresses smaller than bzip2 and decompresses faster, which is why most Linux distributions moved their package compression from bzip2 to xz. bzip2 still shows up in older tooling and pipelines that were built around it.