How to use the tar.gz archive creator
- Choose files, or add a folder to keep its structure. You can add more at any time.
- Set the archive name, the format (.tar.gz, .tgz or plain .tar) and the compression.
- Optionally set a top folder so everything unpacks into one folder.
- Select Create archive and download. Reorder or remove files in the list first if you need to.
Formula
A tar archive is a series of 512-byte headers, each followed by the file data padded to 512 bytes
Each header holds the name, size, modification time and a checksum of its own bytes
The archive ends with two blocks of zeros
Gzip then compresses the whole tar stream; a .tgz is the same file as a .tar.gz with a shorter name
Paths longer than 100 bytes are split at a slash into the name and prefix fields, which allows up to 255 bytes in all.
A small project
Add a folder with a README, a source file and a data file in a sub-folder, set the name to project and the top folder to project, and the page makes project.tar.gz with entries such as project/README.txt and project/data/values.bin. Unpacked with the standard tar command, it produces one folder named project with the same contents and the same modification times.
A file of 1,000 bytes takes 512 bytes for its header and 1,024 bytes of padded data. An empty file takes only its header. A path of 165 bytes in folders is split into a prefix and a name so that it still fits.
Tar and gzip
Tar was made to put many files into one stream, originally for tape. It does not compress anything; gzip does that. Together they give the familiar .tar.gz or .tgz file used for software sources, backups and uploads on Linux, macOS and many servers. Tar keeps file names, folders and modification times, which is why it suits source code and configuration trees better than a plain list of files.
To open an archive someone sent you, use the tar and gzip extractor. If you need a ZIP file for Windows users, use the ZIP file creator. To cut a large file into parts, use the file splitter and joiner.
What the archive keeps
The archive stores each file with permissions set to the common 644 (readable by everyone, writable by the owner), with no owner names, and with the modification time of the file as your browser reports it. It stores regular files only, with no symbolic links or special files. Folder entries are not written; tar creates them when unpacking.
Gzip level 6 is a good balance of speed and size, level 1 is fastest and level 9 the smallest. Already compressed files such as photos, videos and ZIPs gain little. The archive is not encrypted or password protected. Everything is built in your browser and nothing is uploaded.
Assumptions and limits
- Up to 500 files, 25 MB each and 100 MB in total.
- Only regular files are stored, with mode 644 and no owner information.
- File names are stored as UTF-8. Names that cannot be split into a 100-byte name and a 155-byte prefix are refused.
- The gzip header carries no file name or time, so the same input gives the same output.
Frequently asked questions
What is a .tar.gz file?
A tar archive, which bundles files, compressed with gzip. The same as a .tgz.
Can Windows open it?
Recent versions of Windows can open tar files, and archive programs such as 7-Zip can open .tar.gz everywhere.
Does it keep folders?
Yes, if you add a folder or give files paths. The folder structure is stored in the file names.
Are file permissions kept?
No. Every file is stored as 644. If you need executables, set the permissions after unpacking.