File Compressor (Gzip)
Compress a single file with gzip and see exactly how much smaller it gets before downloading.
What is Gzip Compressor?
A one-file gzip compressor. It produces a standard .gz stream that gunzip, 7-Zip, Windows' built-in tar, and every Unix system can open.
How it works
The file is read into memory and piped through the browser's CompressionStream with the gzip wrapper, then handed back as a download with the original filename plus your chosen suffix. The byte counts before and after come from the actual streams, not an estimate.
- 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
gzip or zip — what is the difference?
gzip compresses exactly one stream and stores no filenames, which is why the original name is kept with a .gz suffix. ZIP holds many files plus their names and metadata. For a single log or JSON file, gzip is the smaller and simpler option.
Why did my image barely shrink?
JPEG, PNG, MP4 and friends are already compressed, so there is almost nothing left to squeeze. You get real savings on text, CSV, JSON, XML, logs, SQL dumps and source code.
Is the output a real gzip file?
Yes — a standard RFC 1952 stream, byte-identical in format to what the gzip command produces. Verify it with gunzip -t or by opening it in any archive tool.