`.tar` File Extension

Learn what a .tar file contains, how to open it safely, how Poly supports TAR archives, and when to use a compressed alternative.

File extension details for `.tar`

Storage Only

File type	Tape archive (TAR)
MIME type	`application/x-tar`
Encoding	Binary sequential archive in 512-byte blocks; commonly V7, `ustar`, `pax`, or GNU TAR
Operating systems	Windows, macOS, Linux, Unix
Opens with	GNU tar, Windows tar, bsdtar, 7-Zip
Poly support	Yes. Poly stores, syncs, shares, versions, and downloads `.tar` archives.
Indexed by Poly	Partial. Poly indexes the archive's filename and ordinary file properties, not its members.
Preview in Poly	No. Download the `.tar` file to list or extract it with an archive utility.
Poly agent	No. The Poly agent cannot inspect files packed inside the archive.

What kind of file is a `.tar`?

A .tar file is a TAR archive: one sequential byte stream that bundles files, directories, and Unix-oriented metadata such as permissions, timestamps, ownership, and links. It conventionally uses the application/x-tar MIME type, although that media type is not registered with IANA.¹

TAR is a container, not a compression method. A plain .tar is normally uncompressed. Names such as .tar.gz, .tar.bz2, and .tar.xz describe a TAR stream wrapped in a separate compressor.²

There is no universal magic number for every TAR variant. A ustar archive has the ASCII text ustar at byte offset 257, but older V7 archives do not. Reliable identification also checks the 512-byte header layout, numeric fields, and checksum.³

Renaming backup.zip or backup.tar.gz to backup.tar does not convert or decompress it. Use an archive tool that understands the file's actual contents.

How do I open a `.tar` on my computer?

On Windows, use the included tar command or an archive app such as 7-Zip. Microsoft's command can create, list, and extract .tar files.⁴
On macOS, open the archive with Archive Utility or use tar in Terminal.
On Linux and Unix, use GNU tar, bsdtar, or your desktop's archive manager.

List an unfamiliar archive before extracting it:

tar -tvf archive.tar

Then extract it into a new, empty directory. Check the list for absolute paths, .. parent references, links, device nodes, and unexpected executables. GNU tar recommends isolating untrusted archives because careless extraction can overwrite files outside the intended location.⁵

Poly support for `.tar`

Poly recognizes .tar as an archive and keeps the outer file stored, synced, shared, versioned, downloadable, and searchable by name. It does not unpack the archive, index member names or contents, generate a thumbnail, or provide an in-app member browser. The Poly agent cannot read files that remain inside it.

Upload extracted members separately when you want Poly to preview, index, or reason about their supported contents. A compound file such as backup.tar.gz is handled according to its final compression extension, and its inner TAR members are still not inspected.

History of `.tar`

The name tar comes from “tape archiver.” Early TAR archives carried groups of files on magnetic tape, but the same stream-oriented design also works with regular files and pipes.⁶ Several related layouts developed over time, including the historical Unix V7 format, POSIX ustar, POSIX pax, and GNU extensions.

POSIX standardized ustar in 1988 and later added pax extended headers for values that do not fit fixed-width fields. Modern tools often read several variants, but old readers may not understand long names, large values, or implementation-specific metadata.⁷

Working with `.tar` and alternatives

Choose	Best fit
Plain `.tar`	Streaming, Unix metadata, or a bundle that will be compressed separately
`.tar.gz`	Broadly compatible compressed source releases and backups
`.tar.xz` or `.tar.zst`	Smaller archives or faster modern compression, depending on the codec
ZIP	Familiar cross-platform exchange with per-file compression and quick member lookup

Converting between TAR and ZIP requires extracting and repacking. That process can lose ownership, permissions, hard links, symbolic links, or other metadata that the destination represents differently. TAR's header checksum detects some damage but does not authenticate the sender, so use a separately verified digest or signature when provenance matters.³

Internet Assigned Numbers Authority. Media Types Registry. The application registry does not contain application/x-tar. ↩
GNU Project. Creating and Reading Compressed Archives. The manual explains how compression wraps TAR streams. ↩
GNU Project. Basic TAR Format. The manual documents 512-byte blocks, header fields, ustar, and checksums. ↩ ↩²
Microsoft. tar on Windows. Microsoft documents the included libarchive-based command. ↩
GNU Project. Integrity. The guidance covers isolated extraction, links, absolute names, and overwrites. ↩
GNU Project. What tar Does. The name derives from “tape archiver,” reflecting TAR's original use with magnetic tape. ↩
GNU Project. Controlling the Archive Format. The manual compares V7, ustar, POSIX pax, and GNU formats. ↩

.tar File Extension

File extension details for .tar

What kind of file is a .tar?

How do I open a .tar on my computer?

Poly support for .tar

History of .tar

Working with .tar and alternatives

Footnotes