SPX to GZ Converter
Processing entirely on your device — large files may take a moment.
Unpack a .gz into a normal file or repack it as ZIP/TAR when the receiving tool does not understand gzip. If your files are still in SPX format, this page is the shortcut: SPX is Speex voice audio in an Ogg container — the codec of old VoIP recorders and Asterisk phone systems.
This converter runs entirely in your browser using WebAssembly — your files never leave your device, nothing is uploaded, and there are no watermarks, sign-ups or queues. Drop in several files at once to convert them as a batch.
How SPX compares to GZ
| SPX | GZ | |
|---|---|---|
| Compression | Lossy Speex (Ogg) | DEFLATE |
| Best for | Call recordings, phone systems | Logs, dumps, datasets |
How to convert SPX to GZ
- 1
Select your files
Select your SPX file.
- 2
Convert instantly
The file bytes are gzip-compressed in place — the same archive your server or build tool produces, made locally.
- 3
Download results
Download the .gz file — ready to upload, serve or attach.
About the SPX format
SPX is Speex speech audio in an Ogg container — the open voice codec of the 2000s VoIP wave, tuned for telephone-band speech at absurdly low bitrates. Asterisk PBX call recordings and old conferencing archives are where you meet it.
Speex was formally retired in favor of Opus, and players have followed. Converting SPX to MP3 (or Opus for the adventurous) rescues call archives before they become unplayable.
+Strengths
- ✓Extremely compact for speech
- ✓Open-source lineage
!Limitations
- −Speech-only: music is unusable
- −Format officially retired
About the GZ format
A .gz file is one file squeezed by gzip — not an archive. kernel.org tarballs are “tar inside gz”, but plenty of logs, JSON dumps and CSV exports travel as plain .gz. Opening one means decompressing it back to the original bytes.
Repacking into ZIP or TAR gives the decompressed file a container that every GUI tool opens without a second thought.
+Strengths
- ✓Everywhere on Linux and macOS
- ✓Fast, well-understood compression
- ✓Streams natively from any tool
!Limitations
- −Single file only — no directory tree
- −No encryption or integrity metadata
Why convert SPX to GZ?
Converting makes sense where the strengths of GZ meet what SPX cannot give you. Everywhere on Linux and macOS Meanwhile Speech-only: music is unusable One pass through the converter above puts your file on the right side of that trade-off.
Frequently asked questions
Is this SPX to GZ converter really free?
Yes — completely free, with no sign-up, no watermark and no daily conversion limits. The site is supported by advertising.
Are my files uploaded to a server?
No. The conversion runs entirely inside your browser using WebAssembly, so your files never leave your device — that is what makes it instant and private.
Does it work on Windows, Mac, iPhone and Android?
Yes. Anything with a modern browser works: Windows, macOS, Linux, Android and iOS. No software installation is required.
Is there a file size limit for SPX to GZ?
The only limit is your device's memory, since nothing is uploaded. Files up to a few hundred megabytes work fine on a modern desktop browser; very large files simply take a little longer.
Are the files inside my SPX archive modified?
No. Contents are unpacked in memory and repacked into GZ byte-for-byte — the conversion changes the container, never the files inside it.
What about folders and directory structure?
The full directory tree is preserved: folders stay folders, and deep paths arrive exactly as they were packed in the SPX file.