# .zst MIME Type: application/zstd

> Zstandard-compressed files (RFC 8878): gzip-like speed with much better ratios.

- MIME type: `application/zstd`
- Extensions: .zst
- Content-Type header: `application/zstd`
- Compress in transit: no (already compressed)
- File signature: `28 B5 2F FD`

## Good to know

- Zstandard also works as HTTP compression — Chromium and Firefox accept `Content-Encoding: zstd`. That's separate from serving a `.zst` download as `application/zstd`; see [Content-Encoding](https://www.devkult.com/headers/content-encoding.md).
- `.tar.zst` is now common for distribution packages, including Arch Linux's.

## Server configuration

### nginx (inside the types block in mime.types)

```
application/zstd zst;
```

### Apache (.htaccess or server config)

```
AddType application/zstd .zst
```

### Express

```
res.set("Content-Type", "application/zstd");
```

### Python

```
import mimetypes

mimetypes.add_type("application/zstd", ".zst")
```

### HTML file input

```
<input type="file" accept=".zst,application/zstd">
```

## FAQ

### What is the MIME type for .zst files?

`application/zstd`.

### What Content-Type header should a .zst file be served with?

`Content-Type: application/zstd`. It's already compressed, so servers shouldn't gzip it.

### How can I tell if a file is really a .zst?

Check its bytes rather than the extension: ZST files start with `28 B5 2F FD`. On the command line, `file --mime-type name.zst` does this for you.

## Related types

- [.gz — application/gzip](https://www.devkult.com/mime/gz.md)
- [.xz — application/x-xz](https://www.devkult.com/mime/xz.md)
- [.tar — application/x-tar](https://www.devkult.com/mime/tar.md)

Open the interactive page: https://www.devkult.com/mime/zst