Just Tool It
Just Tool It / Archive Converter
On-device — nothing uploaded

Archive Converter

Repack archives between ZIP, TAR, GZ, 7Z and BZ2 — fully in your browser. RAR archives can be read. Nothing uploaded.

Drop an archive here

or browse from your device — ZIP, TAR, GZ, TGZ, 7Z, RAR, BZ2, TBZ2 — up to your device's RAM

All supported conversions

Every From → To pair the tool supports in your browser. RAR is read-only because its compressor is proprietary — Calibre, 7-Zip and Just Tool It all share this limitation.

Convert archives without uploading

The usual online archive converter uploads your .zip or .rar to a server, runs p7zip on it there, and emails a link to the result. That works — but it leaves a copy of your archive on infrastructure you don't control. For a folder full of resumes, contracts or source code, that's a real privacy concern.

Just Tool It does the entire conversion inside this tab. ZIP, TAR and GZ are repacked using the browser's built-in CompressionStream / DecompressionStream APIs and a small custom header parser — no third-party code involved. For 7Z, RAR and BZ2 we lazy-load 7z-wasm (the official 7-Zip CLI compiled to WebAssembly) on first use. After that, everything runs locally on your CPU. Disconnect from the network and the page still works.

What each format is for

  • ZIP — the universal container. Random-access, Windows-friendly, supported everywhere. Best general-purpose choice.
  • TAR — a plain bundle of files with no compression. The Unix lingua-franca, usually paired with GZ or BZ2.
  • GZ — single-stream Deflate compression. Combined with TAR you get the familiar .tar.gz tarball.
  • 7Z — high-ratio LZMA2 archive. Smaller than ZIP at the cost of slower packing.
  • BZ2 — older single-stream compressor. Still common for source distributions; pairs with TAR as .tar.bz2.
  • RAR — proprietary archive. Readable everywhere, writable only by WinRAR itself. We extract; we don't repack.

How it works (step-by-step)

  1. Drop your archive. The "From" format is auto-detected from the extension — you can override it.
  2. Pick the output format. Any of ZIP, TAR, GZ, 7Z or BZ2. RAR output is impossible everywhere, not just here.
  3. Click Convert. ZIP / TAR / GZ work instantly with the browser's native streams. The first 7Z, RAR or BZ2 operation downloads 7z-wasm (~1 MB) once and caches it.
  4. Download. Multi-file inputs going to GZ or BZ2 produce a .tar.gz / .tar.bz2 tarball, the Unix convention. Single-file inputs stay single-file.

Frequently asked questions

Is my archive uploaded to a server?
No. Your archive is read with the browser's File API and processed in this tab. ZIP, TAR and GZ never make any network request at all. 7Z, RAR and BZ2 fetch the 7z-wasm module once from a public CDN — the engine, not your data — and run it locally afterwards. You can verify with DevTools → Network: clicking Convert never sends your file body anywhere.
Why can't I write RAR?
RAR's compressor is closed-source and proprietary to RARLAB. Only the official WinRAR binary can create RAR files; even 7-Zip and Calibre can only read them. This is not a browser limitation — it's the same on every platform. Convert to ZIP or 7Z if you need a writable container with similar compression.
What does "ZIP → GZ" mean? GZ only holds one file.
Correct — GZ and BZ2 are stream compressors, not multi-file containers. When you convert a multi-file archive to GZ or BZ2 we follow the standard Unix convention: pack the contents as a TAR first, then compress that — producing a .tar.gz / .tar.bz2 file. When the input contains a single file, that file's bytes are compressed directly and you get a plain filename.gz / filename.bz2.
Is there a file-size limit?
Only your device's RAM. The archive is decoded into memory before being repacked, so a 2 GB tarball may need several gigabytes of RAM. Most laptops handle archives up to a few hundred MB comfortably. If a conversion fails with an out-of-memory error, split the archive first on the desktop and convert the parts.
Are file timestamps and Unix permissions preserved?
Modification timestamps round-trip across ZIP, TAR, GZ and BZ2 within the limits of each format. Unix mode bits and ownership are preserved when both ends understand them (TAR ↔ TAR, 7Z ↔ 7Z). Going through ZIP, file modes default to 644 since ZIP's external-attribute field is platform-specific.
Are encrypted / password-protected archives supported?
Not yet. Reading encrypted ZIP, 7Z or RAR would require prompting for a passphrase and we keep the UI minimal for now. If your archive is encrypted the read will fail with a clear error — use a desktop tool to decrypt first, then come back here.