File Decompressor (Gunzip)
Decompress a .gz file back to its original contents, in your browser.
What is Gunzip?
The counterpart to the gzip compressor: it takes a .gz file and gives you back the bytes inside, restoring the filename it was compressed from.
How it works
The file's first bytes are checked for the gzip magic number (1f 8b) before any work starts, so a ZIP or a TAR fails with a clear message instead of a confusing decode error. The stream is then decompressed through the platform DecompressionStream.
- Add your files. Drop files (or a whole folder) onto the drop zone. Browsers hand the contents straight to the page, so nothing is uploaded.
- Choose the options. Pick the format, compression, naming rule or split size. Any change re-computes the preview immediately.
- Download the result. Run the tool and grab the archive, the extracted files or the report. Multi-file results come back as a single .zip.
Examples
A 240 MB photo folder → a 52 MB .zip
JPEGs are already compressed, so the archive only saves 10–15% — but adding the folder structure and a manifest makes the upload verifiable.
A download cut off at 1.4 GB
The File Splitter cuts it into 500 MB chunks that fit the host's limit, and the File Joiner reassembles them, refusing any set with a missing part.
A release bundle with checksums
The Manifest Generator writes sha256sum-style lines next to the files, so the recipient can prove the download arrived intact.
Common mistakes
Expecting ZIP to shrink photos, video or audio
Those formats are already compressed; deflate typically saves single digits on them. ZIP is at its best on text, JSON, CSV, logs and source code.
Treating ZipCrypto as real encryption
Traditional ZIP encryption is legacy and breakable. It stops casual snooping only — for secrets, encrypt the contents with AES-256 first.
Renaming extensions to convert a file
Changing .png to .jpg does not change the bytes inside. Some programs will refuse the file, or display garbage. Use a real converter when the format must change.
Splitting without keeping the suffixes
The parts carry .001, .002 … suffixes on purpose: the joiner orders them by number and fails loudly when one is missing, instead of producing a corrupt file.
Frequently asked questions
It says the gzip header is missing — now what?
The file is not a single gzip stream. A .zip belongs in the ZIP Extractor; a .tar.gz is a gzipped tarball and belongs in the TAR Extractor, which unwraps both layers at once.
How is the output named?
The suffix is removed: access.log.gz becomes access.log, and .tgz becomes .tar. Files with no recognised suffix get .out appended so nothing is overwritten by a nameless download.
Does it handle multi-member gzip files?
Single-stream files are handled, which covers everything gzip and this site produce. Concatenated multi-member streams keep only the first member — rare, and usually a sign the file was glued together by mistake.