Compress or decompress bzip2 (.bz2) files up to 2 GiB in your browser, with a level from 1 to 9.
Runs in your browser — your input is processed on this device and never uploaded.
Pasted text up to 100 MiB, read as UTF-8, or a file up to 2 GiB.
Results appear here.
bzip2 is a compression format from 1996. It sorts each block of data with the Burrows-Wheeler transform before compressing it, which often makes text smaller than gzip does. Files end in .bz2, and source archives often come as .tar.bz2.
This tool compresses bytes into a bzip2 stream, or decompresses a bzip2 stream back to the original bytes.
Plenty of older archives and scientific data sets were made with it, and the bzip2 command is installed almost everywhere. For text it usually beats gzip on size.
In our tests on a desktop computer, 100 MiB of text compressed at level 9 in about 5.5 seconds, to about 22 MiB. Gzip at its default level made about 27 MiB from the same file. Level 6 was barely faster, which is why the default here matches the command.
Zstandard (.zst) is much faster at a similar size. Gzip (.gz) opens almost everywhere. Both have their own tool on this site. XZ (.xz) usually makes smaller files, and this page does not open it.
A .tar.bz2 decompresses here to a .tar file, and so does .tbz2. Opening the archive inside it takes a separate tool.
The bzip2 command on your computer does the same job for files larger than 2 GiB.
Julian Seward released bzip2 in 1996. Michael Burrows and David Wheeler published the transform it is built on in 1994.
Every block carries a CRC checksum, and the stream ends with a combined one, so a damaged or truncated file fails to decode. That does not tell you who made the file, and it is not a signature.
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