Open GZ files on Mac
To open a .gz on Mac, decompress it with gzip or open it in Kernir and extract its contents. A file such as report.csv.gz usually expands to one document. A .tar.gz contains an archive of files and has a separate TAR.GZ workflow.
Work out what is inside
Gzip compresses a stream of data. It does not, by itself, provide the folder tree that ZIP or TAR provides. For report.csv.gz, the expected result is report.csv; for Project.tar.gz, decompression alone can leave you with Project.tar to open next.
File extensions are useful hints, but can be wrong. Kernir detects supported formats from the contents. If it shows a tree of project files rather than one document, the compressed data may be a TAR archive even when the filename is incomplete.
Decompress with Terminal
For report.csv.gz in Downloads, open Terminal and run:
cd ~/Downloads
mkdir "GZ output"
gzip -dc "report.csv.gz" > "GZ output/report.csv"
Use a new destination folder; if GZ output already exists, choose another name before continuing. Replace the input and output filenames to match your document. -d decompresses, and -c sends the result to standard output instead of replacing the source file. The shell's > writes that data to the chosen output.
The original .gz remains. Do not rerun the redirection onto a file you want to keep: > can overwrite it. If decompression reports an error, the output may be partial, so do not treat its existence as proof that extraction succeeded.
The gzip manual describes the command's decompression, output and testing options. Your Mac's installed implementation may differ in additional options, so the example uses the basic read-and-output workflow.
Check a compressed file
You can test the gzip data without writing an expanded file:
gzip -t "report.csv.gz"
Read any error output. A successful integrity test means the compressed data passed that tool's checks; it does not verify the sender or whether a CSV contains the information you expected. Open the extracted document with an appropriate application as a separate step.
If the archive came from a log export, compare dates and expected contents before deleting either copy. Renaming .gz to .txt changes the name, not the compressed data.
Open it in Kernir
The Mac download is coming soon. You can view the source and build instructions on GitHub. These steps describe the current app workflow.
Choose File › Open… (⌘O) and select the GZ. For a standalone stream, Kernir displays its uncompressed content as an entry; the current reader derives that entry's name from the filename without the compression extension. Select it and use File › Extract… (⌘E) to choose where to save it.
Kernir reads standalone GZ but does not write it. You can extract the document or use Save As to create a supported archive such as ZIP. That ZIP is a different format, not an edited GZ. TAR.GZ is separately supported for both reading and writing.
To try a small file with known contents, use the sample archive library. Substitute the downloaded sample's filename in the commands above.
Kernir.dmg, signed and notarized. Requires macOS 14 or later.
Related guides
App steps were checked against Kernir source code. Command examples were checked with test archives on Linux using libarchive and the named utilities, not in a new macOS session. Updated .
