TAR Archive Builder (Browser-Only)

Need to build a tar archive but you're on a machine without tar (Windows, locked-down sandbox, CI debug shell)? This tool packs any selection of files into a POSIX ustar archive directly in your browser. Optional gzip output. Files never leave your machine.

How to use the TAR Archive Builder (Browser-Only)

Click Add files and select one or more files. They appear in the list with their sizes. Pick output format (uncompressed .tar or .tar.gz) and an archive name, then click Build & download.

The output is a standards-compliant POSIX ustar archive — extractable by tar -xf, tar -xzf, 7-Zip, or any other archive tool.

About TAR Archive Builder (Browser-Only)

The tar format (Tape ARchive) is a Unix standard for bundling multiple files into one. Each entry has a 512-byte header followed by the file data (padded to a 512-byte boundary). The header includes filename, mode, owner, group, size, mtime, and a checksum. The archive ends with two 512-byte zero blocks.

The POSIX ustar variant (which this tool produces) adds a magic number "ustar" plus prefix and devmajor / devminor fields, allowing longer filenames and some Unix-specific metadata. It's the de-facto format — every modern tar implementation reads ustar.

For gzip output, the tar archive is wrapped in a single gzip member (RFC 1952). This produces the familiar .tar.gz / .tgz double-extension format. Compression is done via the browser's CompressionStream API (available in all modern browsers).

Limitations: this tool produces a flat archive (no nested directories — files added at root). It supports standard files only (no symlinks, no special files), which is fine for the typical use case of bundling configs / scripts / small text-and-binary collections.

Common use cases

  • Docker build context — bundle config files for docker COPY in a Dockerfile when you can't reach the source tree directly.
  • Embedded firmware — package configuration for devices that consume tar archives.
  • Locked-down CI / sandbox — produce a tar from a browser when shell access is unavailable.
  • Backup snapshots — quick bundle of files for transfer.
  • Education — see how tar headers are laid out (the tool can also export raw bytes for inspection).

Frequently asked questions

Are directories supported?
Not in this version — flat file list only. Bundles typically used for tar archives (configs, scripts) rarely need nested dirs; if you need them, use a desktop tar tool.

What's the maximum file size?
Practically: ~200 MB before browser memory becomes an issue. tar itself supports up to 8 GB per file in ustar (larger via PAX extensions, not implemented here).

Does this support .tar.bz2 or .tar.xz?
No — gzip only. Browser CompressionStream only supports gzip and deflate.

Is the output really standards-compliant?
Yes — extractable by GNU tar, BSD tar, 7-Zip, libarchive, and any other compliant reader. Tested against tar -tvf.