Free ZST Converter: No Sign-up, Files Never Uploaded
Change the format of ZST files for free, with no sign-up and no upload. The conversion happens in this tab, so your files never leave your computer or phone.
Zstandard (ZST) in short. Zstandard: a fast compressor developed at Facebook (Meta). Increasingly used for packages and backups.
From ZST you can convert to ZIP and 7Z. Every of these pairs can need a one-time engine download, which the page announces before it starts.
ZST is a source format here. ZST can be opened but not created here; use ZIP or TAR.GZ.
- Free
- No sign-up
- Never uploaded
- No watermark
Your files are converted on your device and never uploaded.
How to convert
- Add your ZST files by dragging them onto the converter or by using the file picker.
- Choose the format you want from the list of targets that fit your file.
- Open the options if you want to change quality or size, or keep the defaults.
- Press Convert and watch the progress shown for each file.
- Download each result, or take them all together as one ZIP when you converted several files.
Features
- Reads .zst files.
- Free, with no watermark added to the result.
- No sign-up and no login.
- Your files are never uploaded and never leave your device.
- Batch conversion with a ZIP download for several results.
- The input is recognised by its content, not only by its file name.
- 2 target formats to choose from.
- A one-time engine download is cached by your browser.
Supported formats
| Format | Read | Write | Notes |
|---|---|---|---|
| ZIP.zip | Yes | Yes | The most common archive format, opened natively by Windows, macOS and Linux. |
| 7-Zip (7Z).7z | Yes | Yes | Archive format of the 7-Zip tool, usually the smallest of the common formats. |
| RAR.rar | Yes | No | RAR is a proprietary format: its encoder is not available, so RAR files can be opened but not created. |
| TAR.tar | Yes | Yes | Tape Archive: bundles files together without compressing them. |
| GZ.gz | Yes | Yes | gzip compresses a single file or stream, and is the compression behind .tar.gz. |
| TAR.GZ.tgz | Yes | Yes | A TAR archive compressed with gzip. |
| BZ2.bz2 | Yes | No | BZ2 can be opened but not created here; use ZIP or TAR.GZ. |
| XZ.xz | Yes | No | XZ can be opened but not created here; use ZIP, 7Z or TAR.GZ. |
| LZMA.lzma | Yes | No | LZMA can be opened but not created here; use 7Z or ZIP. |
| Zstandard (ZST).zst | Yes | No | ZST can be opened but not created here; use ZIP or TAR.GZ. |
| Cabinet (CAB).cab | Yes | No | CAB can be opened but not created here; use ZIP. |
| ISO disc image.iso | Yes | No | ISO images can be opened but not created here; extract the files and use ZIP. |
| CPIO.cpio | Yes | No | CPIO can be opened but not created here; use TAR or ZIP. |
| TAR.BZ2.tbz | Yes | No | TAR.BZ2 can be opened but not created here; use TAR.GZ. |
| TAR.XZ.txz | Yes | No | TAR.XZ can be opened but not created here; use TAR.GZ. |
About the formats
About ZST
Zstandard: a fast compressor developed at Facebook (Meta).
Increasingly used for packages and backups.
It does not support transparency.
What ZST can become
ZST to ZIP can need a one-time download of about 1.5 MB.
ZST to 7Z can need a one-time download of about 1.5 MB.
Why ZST is read only
ZST can be opened but not created here; use ZIP or TAR.GZ.
Privacy: how it works
- Your ZST files stay on your device. The page reads each file with the browser's file API, converts it with code running in the tab, and hands the result back as a download. No upload happens, so there is no copy of your file on our servers to protect, delete or leak.
- There is nothing to sign up for and no login. The converter does not ask for an email address, and it does not need to know who you are to do its job.
- Some conversions use a WebAssembly engine that your browser downloads once, the first time you need it. Only the engine is fetched, never your file, and the page shows the approximate size before it starts. Your browser caches it, so later conversions skip the download.
- You can check the claim yourself: open your browser developer tools, watch the Network tab while a file converts, and you will see no request that carries your file.
Tips
- Check that the converted archive opens and holds the files you expect before you delete the original.
- File names with unusual characters can differ between formats, so test a copy first.
- Password-protected archives cannot be read until they are unlocked.
- Keep the original archive until you have checked the result.
- ZST cannot be created here, so pick one of its targets instead.
Frequently asked questions
Is it really free?
Yes. There is no price, no trial, no credit card and no watermark added to your results. Ulkaa Tool does the conversion with your own device, so there is no server bill to pass on to you.
Are my files uploaded?
No. Your ZST files are read and converted inside your browser and are never sent to Ulkaa or to anyone else. The result is created on your device and you save it from there. Some conversions load a small conversion engine the first time you use them. That download is the only network traffic, it contains no file of yours, and your browser keeps it for next time.
Do I need an account?
No. There is no sign-up and no login. Open the page, add your files and convert. An Ulkaa account is not needed for anything on this tool.
Is there a file size limit?
No limit is set by us. The real limit is your device: the conversion uses your own memory and processor, so very large files can be slow or fail on a weak phone or an older computer. Close other heavy tabs and convert ZST files one at a time if a big batch struggles.
What can I convert ZST files to?
You can convert ZST to ZIP and 7Z. Pick one on the converter and it applies to every file you add.
Can I convert other files to ZST?
No. ZST can be opened but not created here; use ZIP or TAR.GZ.
Can I convert many ZST files at once?
Yes. Add as many files as your device can handle. Each one is converted on its own and you can download them one by one or as a single ZIP.